Using the Stepper Motor (SM) eTPU Function
Contents
1. I J 7 O O a Figure 4 Half step unipolar drive of a 2 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 7 Function Description pin_ sequence Ox O C 3 O C 3 QOQOO0 1100001 100001100001 1 direction of rotation gt FEDCBA generated ALGOT TLO MLO MmU signals B C D E F step 123456 motor bridge motor model ai tat t rotor stepping ory pile amp ye 4 Eve 3a en INS on AON ae Pee 345 3m Figure 5 Full step bipolar drive of a 3 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 8 Freescale Semiconductor Function Description pin_ sequence Ox O CI 3 O CI 3 00001 100001 100001 100001 1 direction of rotation gt FEDCBA generated A L TLG TLO ML signals B C D z F step 123456 motor bridge motor model k amp F EA A fa BS i j rotor stepping ae ge gt sve 4 ASS 345 a 385 OntrBRwWNM Sra wae oS ae ns Figure 6 Full step unipolar drive of a 3 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 9 Function Description pin_sequence Ox2. and 64 95 for ETPU_B with respect to the number of following slave channels The slave channels are defined immediately after the master in numeric order polarity uint8_t This is the polarity of the generated signals This parameter can be assigned a value of FS ETPU_SM ACTIVE HIGH FS ETPU_SM ACTIVE LOW Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor C Level API for Function 4 2 3 void fs_etpu_sm_set_dp uint8_t channel int24_t desired_position This function sets where to move the stepper motor and the command for movement This function has the following parameters e channel uint8_t This is the SM master channel number This parameter must be assigned the same value that is assigned to the channel parameter in the initialization routine If there are more SMs running simultaneously on the eTPU s the channel parameter distinguishes which SM function is accessed e desired_position int24 t This is the desired position that the motor should move to After etpu_sm_set_dp is called the motor moves until there is a match between the current_position and the desired_position Also the etpu_sm_set_dp function can be called at any time even when the motor is stepping towards another value The SM function will automatically take care of slowing the motor reversing the direction if necessary and accelerating towards the new desired_position as needed 4 2 4 void fs_etpu
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4. _handlers c This file contains the general interrupt handlers pcemaster This folder contains FreeMaster HTML page source 1lcf This folder contains the Metrowerks linker command files MCF523xEVB configuration etc The eTPU initialization consists of two function calls First the my system _etpu_init function is called and second after initialization of all other peripherals the eTPU is started by my system etpu s my system etpu s included in 3phase_sm_etpu_gct c file Graphical Configuration Tool can be downloaded from http www freescale com 6 2 1 fs_etpu_sm_init iB j i A 7 m j j channel configuration start position start period start period slew period p_accel tbl accel tbl size fs_etpu_sm_ enable channel priority configuration xy xJ f f af 7 f af af tart Bothmy system etpu init and tart functions are generated by eTPU Graphical Configuration Tool and are Function Calls SMO A MASTER FS ETPU SM 3PHASE HALF STEP 0 etpu_a_tcrl freq StartFrequency etpu_a_tcrl freq StartFrequency etpu_a_tcrl freq SlewFrequency accel tbl SM ACCEL TABLE SIZE SMO A MASTER FS_ETPU_ PRIORITY MIDDLE FS ETPU SM 3PHASE HALF STEP Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 23 Summary and Conclusion
5. only be changed between moves and not while the motor is running 4 3 Value Return Functions 4 3 1 int24_tfs_etpu_sm_get_dp uint8_t channel This function reads the desired_position and contains the following parameter e channel uint8_t This is the SM master channel number This parameter must be assigned the same value as was assigned to the channel parameter in the initialization routine If there are more SMs running simultaneously on the eTPU s the channel parameter distinguishes which SM function is accessed The value of the desired_position is returned as an int24 t 4 3 2 int24_t fs_etpu_sm_get_cp uint8_t channel This function reads the current_position of the SM that can be used for program control when compared against the desired_position or some other value This function has the following parameter e channel uint8_t This is the SM master channel number This parameter must be assigned the same value as was assigned to the channel parameter in the initialization routine If there are more SMs running simultaneously on the eTPU s the channel parameter distinguishes which SM function is accessed The value of the current_position is returned as an int24 t 4 3 3 uint8_t fs_etpu_sm_get_flags uint8_t channel This function reads the status flags of the SM There are the following flags STEPPING indicates if the motor is currently stepping or not DIRECTION distinguishes if the motor is going in a dec
6. the service time latency of other active eTPU channels This is due to the operational nature of the scheduler When a single SM function is in use and no other eTPU channels are active the minimum time between any two steps must be greater than 210 eTPU instruction cycles For the MPC5554 with a system frequency of 128 MHz the maximum step frequency is 304 700 steps per second For the MCF5235 with a system frequency of 150 MHz the maximum step frequency is 178 500 steps per second When more eTPU channels are active performance decreases In order to ensure the correct functionality of the SM make sure that the slew period is longer or equal to the worst case latency of the SM master channel Maximum step frequency is influenced by compiler efficiency The above numbers are given for guidance only and are subject to change For up to date information refer to the information provided in the eTPU SM software release available from Freescale 4 C Level API for Function The following routines provide easy access to the SM function for the application developer Use of these functions eliminate the need to directly control the eTPU registers There are six functions added to the application programming interface API The routines can be found in the etpu_sm h and etpu_sm c files which should be included in the link file along with the top level development file s These routines use standard eTPU utilities that are located inthe etpu_util ha
7. Freescale Semiconductor AN2869 Application Note Rev 0 1 04 2006 Using the Stepper Motor SM eTPU Function Covers the MCF523x MPC5500 and all ef PU equipped devices by Milan Brejl System Application Engineer Roznov Czech System Center 1 Introduction Table of Contents uiidole Gla alaeeeeeerrererrerarertce i 1 Function OVVIE W iccnsorsiiesslecsqrigunspratiasoneosdeqaiies 1 Function Descriptores ar 2 C Level API for PunCHON cscs 12 TPU Compatible C Level API 17 Example Use of Function s ccisscorssessceesscssanccteess 19 Summary and Conclusions ceeeeeeeee 24 The stepper motor SM Enhanced Time Processor Unit eTPU function is one of the functions in the standard set of eTPU functions set1 This application note is intended to provide simple C interface routines to the SM eTPU function The routines are targeted at the MCF523x family of devices but they could be easily used with any device that contains an eTPU NOOR WD 2 Function Overview The SM function provides the eTPU with the capability of driving two phase or three phase stepper motors in full step or half step modes The eTPU can accelerate the motors run them at constant speed or slew and decelerate the motor independently of the device s CPU The CPU need only initialize the function once and then supply a desired position each time a move is required The acceleration deceleration profile is freely configured by the user via a tab
8. O O 7 O O 7 0000000001 11000000000111 1 direction of rotation gt A E D CBA generated A TI Lon i signals B C D E E step 12345678910112 motor bridge motor model OO AON Vw P ae IO OY N A LY x Do r NE E a OON O a Gc smc 28 Cc amr 0C Ess 7 amp ne Jc Oy N 7 Figure 7 Half step bipolar drive of a 3 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor pin_ sequence generated signals motor bridge Function Description o O 0 7 0 0 7 o0o000000011 1000000000111 direction of rotaion gt FF E D CBA To Pop a ee mMmOQOWw gt S gt F step 12345678910112 motor model OntrBRwWDNM Figure 8 Half step unipolar drive of a 3 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor C Level API for Function pin_ sequence Ox A A A A ATLA 10101010101010101010101 direction of rotation gt gt O generated signal A JUUN ununun step 1234 Figure 9 General drive of a stepper motor using an external driver clocked by the eTPU 3 2 Performance Like all eTPU functions the SM function performance in an application is to some extent dependent upon
9. Stimulator Desired Position commands stimulators R5232 COM1 speed 19200 Scope Running Figure 12 FreeMaster application window For download and more information about FreeMaster visit http www freescale com 6 2 Application Code The demo application consists of the following files and folders e 3phase_sm mcp The Metrowerks project file e 3phase_sm pmp The FreeMaster project file e src tThis folder contains the application source code etpu This folder contains the eTPU files etpu_set1 h This file contains the standard eTPU function set set1 code image etpu_sm c h These files contains the SM API functions etpu_sm_auto h This file was automatically generated by the eTPU code compiler 3phase_ sm _etpu_gct c h These files contain initialization of eTPU for this Using the Stepper Motor SM eTPU Function Rev 0 1 22 Freescale Semiconductor Example Use of Function application They were originally generated by the eTPU Graphical Configuration Tool etpu_util c h These files contain useful macros and prototypes for using the eTPU typedefs h This file contains type definitions pcmaster This folder contains FreeMaster routines for MCF523x init This folder contains MCF523x header files etc main c h This is the main application file and its header file vectors s This file contains the vector table int
10. _sm_set_sp uint8_t channel int24_t slew_period The slew period parameter specifies the minimum step period of the motor and therefore its maximum speed e channel uint8_t This is the SM master channel number This parameter must be assigned the same value as was assigned to the channel parameter in the initialization routine If there are more SMs running simultaneously on the eTPU s the channel parameter distinguishes which SM function is accessed e slew_period int24_t Slew period as a number of TCRI ticks If the application uses frequencies in Hz instead of periods in TCR1 cycles one of the following expressions can be used instead of slew_ period etpu_a_tcrl freq slew frequency etpu b tcrl freq slew frequency The slew_period parameter is used under two circumstances 1 The end of the acceleration table is reached 2 The period value obtained from the fractional multiplication of the start_period value by an acceleration parameter from the table is less than slew_period This allows the slew_ period to be used to limit the maximum speed of a particular motor when multiple motors are sharing a common acceleration table The slew_period also allows a motor to make moves of the same length at different speeds without requiring a reprogramming of the acceleration table Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 15 C Level API for Function NOTE slew_period should
11. e on six LEDs that are connected to eTPU channels 8 to 13 Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 19 Example Use of Function 2 Sale Boe alesse Fale cole Desired Positi LEDs FreeMaster M RS 232 Interface BDM Interface Figure 10 SM demo application on MCF523xEVB The application demonstrates how to initialize the eTPU module and assign the SM function to eTPU channels After initialization an application state machine is started Within the state machine the SM function is enabled and disabled based on ON OFF switch moves When the application is in APP_STATE ON the SM function can be commanded to move to a desired position The application state machine consists of the following states and is illustrated in Figure 11 e APP STATE_OFF SM eTPU channels are disabled If the ON OFF switch is moved to the ON position go to the APP_ STATE ENABLE e APP STATE_ENABLE Enable the SM eTPU channels and go to APP STATE ON Using the Stepper Motor SM eTPU Function Rev 0 1 20 Freescale Semiconductor Example Use of Function e APP STATE _ON The SM eTPU channels are enabled The SM function can be commanded to move to a given position If the ON OFF switch is moved to the OFF position go to the APP_STATE DISABLE e APP STATE_DISABLE Disable the SM eTPU channels and go to APP_STATE_ OFF e APP STATE_FAULT Disable the SM eTPU c
12. e size and the table index values into a single 16 bit input The first 8 bits the table size is the number of steps defined in the acceleration table The table index is set in the last 8 bits of this parameter and must be set to the value of zero slew_period Combines the slew period with the 1 bit S value The slew period value must be shifted left by 1 bit after encoding into a hex value For example an original value of 2000 will be encoded as 4000 The least significant bit is an S bit and must always be written as zero and only at initialization start_period Combines the start period with the 1 bit A value The start period value must be shifted left by 1 bit after encoding into a hex value For example an original value of 6800 will be encoded as D000 The least significant bit is an A bit A value of 0 will initialize a two channel TSM function and a value of will initialize a four channel function This value must not be changed after initialization pin_sequence Determines the step patterns that are output on two or four TPU pins Two channel and four channel example values are 3333 and EOEO respectively number_channels Used with the master channel designation to determine which channels will be the parameter table channels for the TSM function Either a two or four channel designation is valid The master channel is included in this number table The pointer to the acceleration table table_size Not
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14. equence in the full step drive of a 2 phase motor then the master channel is initialized pin high according to bit 0 of the pin sequence and the following slave channel is also pin high according to bit 1 of the pin sequence see Figure 1 To change the initial pin states replace the pin sequence by one of its rotated versions 0x666666 0OxCCCCCC or 0x999999 in etpu_sm h file To generate a step the pin sequence is rotated left or right once depending on the motor direction left when direction is decremental right when direction is incremental The master channel pin level for the next step is defined by the LSB of the rotated pin sequence The pin levels of the slave channels are determined by the next bits of the pin sequence In full step mode every bit is used In half step mode every second bit is used The figures show the effective positions of the bits that determine the pin levels of the master and slave channels Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 3 Function Description pin_ sequence Ox 3 3 3 3 3 3 l O01 10011001 100110011001 direction of rotation gt BA generated A signals B step 1234 motor bridge model motor model os O l N L_ gt oO iN L_ gt A OO NO rotor stepping step ae 2 3 4 43 amp iE 2g N 3e Eg Figure 1 Full s
15. f the motor When accelerating the eTPU uses a new value from the acceleration table for each step until the calculated step period table parameter x start period is smaller than the slew period When this point is reached the eTPU switches to the slew period The eTPU also uses the slew period if it reaches the end of the acceleration table The slew period parameter allows the terminal speed of the motor to be controlled independently of the acceleration table length and content Using the Stepper Motor SM eTPU Function Rev 0 1 2 Freescale Semiconductor Function Description 3 1 Example Configurations The SM function is designed to provide as much flexibility as possible in the generation of the step patterns that drive the motor This flexibility allows the SM function to meet the needs of unusual drive schemes However since the primary purpose of the SM function is to drive stepper motors in a conventional manner it has been tested using the configurations depicted in Figures to 9 Each of the configurations defines a pin sequence number of channels and mode full step half step The bipolar and unipolar versions of any configuration are the same from the eTPU point of view because the generated step patterns are equal in both versions During initialization each SM channel pin is initialized low or high to match the value of the corresponding channel bit in the pin sequence For example if 0x333333 is the initial pin s
16. hannels If the ON OFF switch is moved to the OFF position go to APP_STATE_ OFF This state is entered if the ON OFF switch is in the ON position at the time when the application is started Out of the application state machine the current position and the SM flags are read a APP_STATE_ON he fs_etpu_sm_set_dp ON OFF switch moved OFF APP_STATE_ENABLE APP_STATE_FAULT APP_STATE_DISABLE fs_etpu_sm_enable fs_etpu_sm_disable fs_etpu_sm_disable ON OFF switch moved OFF ON OFF switch APP_STATE_OFF Figure 11 Demo application state machine The user interface is made using the ON OFF switch on MCF523xEVB and FreeMaster application on PC FreeMaster communicates with the MCF523xEVB through the RS 232 serial line FreeMaster enables to set the desired position and displays the current position and SM flags Moreover FreeMaster depicts the desired and the current positions in a time chart Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 21 Example Use of Function F 3phase_sm pmp FreeMaster 0 x File Edit View Scope Item Project Tools Help co NOI Halal el gt aA le Aee i 16 ge frame ew zl ul ele Ee Sz a Es 3 phase Stepper Motor Desired Position Current Position Scope D Q fey O A a Ww ao N O Position ax So a Time sec control page oscilloscope
17. ion 3 2 changed 304 700 and 178 500 steps to 304 700 and 178 500 steps 0 10 2004 Initial customer release version Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 25 How to Reach Us Home Page www freescale com E mail support freescale com USA Europe or Locations Not Listed Freescale Semiconductor Technical Information Center CH370 1300 N Alma School Road Chandler Arizona 85224 1 800 521 6274 or 1 480 768 2130 support freescale com Europe Middle East and Africa Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muenchen Germany 44 1296 380 456 English 46 8 52200080 English 49 89 92103 559 German 33 1 69 35 48 48 French support freescale com Japan Freescale Semiconductor Japan Ltd Technical Information Center 3 20 1 Minami Azabu Minato ku Tokyo 106 0047 Japan 0120 191014 or 81 3 3440 3569 support japan freescale com Asia Pacific Freescale Semiconductor Hong Kong Ltd Technical Information Center 2 Dai King Street Tai Po Industrial Estate Tai Po N T Hong Kong 800 2666 8080 support asia freescale com For Literature Requests Only Freescale Semiconductor Literature Distribution Center P O Box 5405 Denver Colorado 80217 1 800 441 2447 or 303 675 2140 Fax 303 675 2150 LDCForFreescaleSemiconductor hibbertgroup com Information in this document is provided solely to
18. le of step rates The SM eTPU function is based on the table stepper motor TSM TPU function The SM eTPU function Freescale Semiconductor Inc 2004 2006 All rights reserved pe freesca le semiconductor Function Description expands the TSM TPU functionality in the following items e Support of 3 phase motors e Acceleration table size is unlimited limited only by the amount of available memory e 16 bit acceleration ratios e 24 bit position values current position and desired position 3 Function Description The SM function supports full and half step unipolar and bipolar driving of two or three phase stepper motors using one two four or six adjacent eTPU channels Given a move request by the CPU the eTPU independently accelerates slews and decelerates the motor to the desired position thus relieving the CPU of almost all overhead associated with controlling the motor The current motor position is maintained by the eTPU as a 24 bit parameter that can be read by the CPU at any time The CPU requests a move by writing a 24 bit desired position value When the eTPU has completed moving the motor to the desired position it issues an interrupt request to the CPU If the appropriate interrupt enable bit is set then a CPU interrupt will result allowing optional interrupt driven control The algorithm employed in the eTPU re evaluates the requested destination on every step This means that the CPU can change
19. ndetpu_util c files The routines will be described in order and are listed below e Initialization Function int32 t fs etpu_sm_init uint8 t channel uint8 t configuration int24 t start position int24 t start period int24 t slew period Using the Stepper Motor SM eTPU Function Rev 0 1 12 Freescale Semiconductor C Level API for Function const uintl6 t p accel tbl uintl6 t accel tbl size e Change Operation Functions void fs etpu_sm enable uint8 t channel uint8 t priority void fs etpu_sm disable uint8 t channel uint8 t polarity void fs etpu sm set dp uint8 t channel int24 t desired position void fs etpu_sm_set_sp uint8 t channel int24 t slew period e Value Return Functions int24 t fs etpu sm get dp uint8 t channel int24 t fs etpu sm get cp uint8 t channel uint8 t fs etpu sm get flags uint8 t channel 4 1 Initialization Function 4 1 1 int32_t fs_etpu_sm_init This routine is used to initialize the eTPU channels for the SM function The SM eTPU channels must be initialized once and then can be repeatedly enabled and disabled by fs etpu_sm_enable and fs etpu sm disable functions This function has the following parameters e channel uint8_t This is the SM master channel number This parameter should be assigned a value of 0 31 for ETPU_A and 64 95 for ETPU_B with respect to the number of following slave channels The slave channels are defi
20. ned immediately after the master in numeric order e configuration uint8_t This is the pre defined configuration parameter This parameter should be assigned a value of FS ETPU_SM 2PHASE FULL STEP FS ETPU_SM 2PHASE HALF STEP FS ETPU_SM 3PHASE FULL STEP FS ETPU_SM 3PHASE HALF STEP FS ETPU_SM EXT DRIVER The pre defined configurations correspond to the examples described in Section 3 1 Example Configurations and pre define the number of channels used the pin sequences and the mode full step half step If an application requires a change to a configuration edit the pre defined values in the fileetpu_sm h e start_position int24_ t This is the starting current_position value e start_period int24_t This is the start period as a number of TCR1 ticks The start period is the first and last step period of a movement If an application uses frequencies in Hz instead of periods in TCR1 cycles one of the following expressions can be used instead of start_period etpu_a_tcrl freq start_ frequency Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 13 C Level API for Function etpu_b tcrl_ freq start_ frequency slew_period int24_t This is the slew period as a number of TCR1 ticks The slew period is the step period when the motor rotates at max speed The slew period is the shortest period of a movement If an application uses frequencies in Hz instead of period
21. remental left direction or an incremental right direction SLEW indicates if the motor is currently in a slew rate This function has the following parameter e channel uint8_t This is the SM master channel number This parameter must be assigned the same value as was assigned to the channel parameter in the initialization routine If there are more SMs running simultaneously on the eTPU s the channel parameter distinguishes which SM function is accessed The flags are returned as an int8 t The following examples show how the returned flags value can be used for program control The flag masks and flag values defined in etpu_ sm h are used Using the Stepper Motor SM eTPU Function Rev 0 1 16 Freescale Semiconductor TPU Compatible C Level API if flags amp FS _ETPU_SM STEPPING FS ETPU SM STEPPING ON esae if flags amp FS_ETPU SM STEPPING FS ETPU SM STEPPING OF vss if flags amp FS ETPU_SM DIRECTION FS ETPU SM DIRECTION DEC if flags amp FS _ETPU_SM DIRECTION FS ETPU SM DIRECTION INC if flags amp FS ETPU SM SLEW FS ETPU SM SLEW ON ERE if flags amp FS ETPU SM SLEW FS ETPU SM SLEW OFF Gesi 5 TPU Compatible C Level API The TPU compatible API provides backward compatibility from eTPU to TPU The following functions allow control of the eTPU SM function using the TPU TSM API func
22. s F fs _ etpu sm disable channel SMO A MASTER configuration FS ETPU SM 3PHASE HALF STEP polarity FS ETPU SM ACTIVE HIGH e fs etpu sm set dp channel SMO A MASTER desired position DesiredPosition Le CurrentPosition fs etpu sm get cp channel SMO A MASTER Flags fs etpu sm get flags channel SMO A MASTER 7 7 Summary and Conclusions This application note provides the user with a description of the stepper motor SM eTPU function usage and examples The simple C interface routines to the SM eTPU function enable easy implementation of the SM in applications The demo application is targeted at the MCF523x family of devices but it could be easily reused with any device that has an eTPU References 1 Moe MCF5235 Reference Manual MCF5235RM D M523xEVB User s Manual M5235EVBUM D FreeMaster web page http www freescale com search keyword FreeMaster Enhanced Time Processing Unit Reference Manual ETPURM D eTPU Graphical Configuration Tool http www freescale com search keyword ETPUGCT Using the Stepper Motor SM eTPU Function Rev 0 1 24 Freescale Semiconductor Revision History 8 Revision History Table 1 provides a revision history of this document Table 1 Revision History Rev Date of Number Release Substantive Changes 0 1 04 2006 In sect
23. s in TCR1 cycles one of the following expressions can be used instead of slew_period etpu_a_tcrl freq slew frequency etpu b tcrl freq slew frequency accel_tbl const uint16_t This parameter is the pointer to the acceleration table The acceleration table is an array of unsigned fract16 The nth step period results from the fractional multiplication of the start_period and accel_tbl n accel tbl size uint16_t This parameter is the acceleration table size as a number of 16 bit acceleration steps 4 2 Change Operation Functions 4 2 1 void fs_etpu_sm_enable This routine is used to enable the SM eTPU channels This function has the following parameters channel uint8_t This is the SM master channel number This parameter should be assigned a value of 0 31 for ETPU_A and 64 95 for ETPU_B with respect to the number of following slave channels The slave channels are defined immediately after the master in numeric order priority uint8_t This is the priority to assign to the SM function The eTPU priority definitions are defined in etpu_utils h FS _ETPU PRIORITY HIGH FS ETPU PRIORITY MIDDLE FS ETPU PRIORITY LOW FS ETPU PRIORITY DISABLED 4 2 2 void fs_etpu_sm_disable This routine is used to disable the SM eTPU channels This function has the following parameters channel uint8_t This is the SM master channel number This parameter should be assigned a value of 0 31 for ETPU_A
24. tep bipolar drive of a 2 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor Function Description pin_ sequence Ox 3 3 3 S 3 3 DOW TOOT TOO LOO TOO TOORN direction of rotation generated A signals B step 1234 motor bridge model motor model RwOtFD a rotor stepping step A 2 3 4 3g aXe 3c is Figure 2 Full step unipolar drive of a 2 phase motor Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor Function Description pin_ sequence Ox O 7 O 7 O 7 000001 1100000111000001 11 direction of rotation gt D CBA generated A signals B C D step 12345678 motor bridge model motor model A C B a 2 ta 2 C A D B rotor stepping step M el E A A amp E DPC Age ame Eg a E p h dE ag Ifc a l Figure 3 Half step bipolar drive of a 2 phase motor j E y By T Using the Stepper Motor SM eTPU Function Rev 0 1 6 Freescale Semiconductor Function Description pin_ sequence Ox O 7 O 7 O 7 000001 110000011 100000111 direction of rotation gt D CBA generated A signals B C D step 12345678 motor bridge model motor model A OFN et al el rotor stepping step 1 2 pole i Il A Pi 5 _ 6
25. the desired position at any time during a movement and the eTPU will adjust its strategy to get to the new desired position as quickly as possible For example if the motor is currently moving clockwise from position A to position B at a given slew rate when the CPU writes a new desired position C which is anticlockwise from the current position the eTPU will immediately decelerate the motor reverse direction accelerate slew and decelerate in the anticlockwise direction to reach position C The SM function generates the actual step patterns to drive the motor via synchronized output matches on a defined number of channels The step patterns generated are defined by the user The SM function operates on a master channel and an adjustable number of slave channels The master channel is chosen by the user and the slave s are then defined immediately after the master in numeric order The SM function uses the same user defined step period profile during acceleration and deceleration The user specifies this profile via a table in eTPU DATA RAM A 24 bit start period defines the period of the first and last steps in any move i e the start stop rate pull in rate of the motor The acceleration profile is programmed into a table of 16 bit constants they are used sequentially to fractionally multiply the start period during acceleration to obtain the n step period The user also specifies a slew period that defines the exact maximum running speed o
26. tion calls e Jnitialization Function void tpu tsm init struct TPU3 tag tpu UINT8 channel UINT8 priority INT16 start position UINT16 table size index UINT16 slew period UINT16 start period UINT16 pin sequence UINT8 number channels UINT16 table UINT8 table size e Change Operation Functions void tpu tsm mov struct TPU3 tag tpu UINT8 channel UINT16 position e Value Return Functions UINT16 tpu tsm rd dp struct TPU3 tag tpu UINT8 channel UINT16 tpu tsm rd cp struct TPU3 tag tpu UINT8 channel 5 1 Initialization Function 5 1 1 void tpu_tsm_init This routine will initialize the channels of the eTPU for the SM function in the same way as for the TPU TSM function This function has the following parameters e tpu Not used e channel The channel number of the SM master channel e priority The priority level which is assigned to all channels used for this SM function This parameter should be assigned a value of FS_ETPU PRIORITY HIGH FS_ETPU PRIORITY MIDDLE or FS_ETPU PRIORITY LOW Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor 17 TPU Compatible C Level API 5 2 5 2 1 start_position A 16 bit integer which establishes the initial value for both the desired position and the current position This is efficient since both values need to be set to the same value when the SM function is initialized table_size_index Combines the tabl
27. used Change Operation Functions void tpu_tsm_mov struct TPU3_tag tpu UINT8 channel UINT16 position This function will designate where to move the stepper motor This is accomplished by the following input parameters tpu Not used channel The channel number of the SM master channel position The value of the new desired position Using the Stepper Motor SM eTPU Function Rev 0 1 Freescale Semiconductor Example Use of Function 5 3 Value Return Functions 5 3 1 UINT16 tpu_tsm_rd_dp struct TPU3_tag tpu UINT8 channel This routine will read the value of the desired position which is used for program control when compared against some other value e tpu Not used e channel The channel number of the SM master channel The value of the desired position is returned as an UINT16 function 5 3 2 UINT16 tpu_tsm_rd_cp struct TPU3_tag tpu UINT8 channel This routine will read the value of the current position which is used for program control when compared against some other value e tpu Not used e channel The channel number of the SM master channel The value of the current position is returned as an UINT 16 function 6 Example Use of Function 6 1 Demo Application This section describes an example application which is created using Metrowerks CodeWarior 4 0 and runs on MCF523x Evaluation Board MCF523xEVB Even if no stepper motor is connected the stepping pattern is clearly visibl
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