XACTUAL only increments

Hi, 

XACTUAL counts up in right direction (positive velocity) and counts down in left direction. Please be sure to interprete the number as a 2's complement signed integer. 

BTW, just looked at your background. Pretty impressive. I love this chip.

Thank you :-)

I guess, that then probably not the counting is wrong, but motion command is just in one direction. BTW, normally, you would not change XACTUAL, except for a single time, when homing. You then instead would modify XTARGET and command the motion controller to move to it. When changing XACTUAL, motion would try to move to XTARGET again.

I made a little progress and learned a few things. I did write a small test program and realized XACTUAL does increment and decrement in forward and worse for target mode. Where I'm having the issue is in velocity mode. Does velocity increment and decrement depending on direction? In case it matters, I'm using a TMC4361A-BOB. I've include code snippets for my test program as well as the output.

For some reason, I can insert the .h files and output files but not the .c files.

#include <gtk/gtk.h>
#include <stdio.h>
#include <wiringPi.h>
#include <stdlib.h>
#include "bcm2835.h"
#include <linux/i2c-dev.h>
#include <i2c/smbus.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <linux/i2c.h>
#include <signal.h>
#include "tmc4361spi.h"
//#include "SPI_TMC.h"
#include <stdint.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/spi/spidev.h>
#include <pigpiod_if2.h>
#include "TMC-API/tmc/ic/TMC4361A/TMC4361A_Register.h"
#include "TMC-API/tmc/ic/TMC4361A/TMC4361A.h"
#include "TMC-API/tmc/helpers/API_Header.h"
//#include "Mcp23017.h"

#define PRIMARY_CLOCK_SPEED   (4800000)

#define OK                    (1)

#define MOTOR0			         (0) // Motor 0
#define CW                    (0)
#define VELOCITY              (0)
#define FORWARD               (1)
#define REVERSE               (0)

#define MOTION_ENABLE         (1)

#define RESET_GPIO_PIN 17

#define STOP                  (0)

static int spiFdY = -1; // Standard Linux SPI file descriptor

float yCommandedPos;

gboolean yTrajectory;

uint8_t buffer[2];                              // Initialize a buffer for two bytes to write to the device

void resetMotorDrivers();

void signal_callback_handler(int signum);

#include "TMC-API/tmc/ic/TMC4361A/TMC4361A_Register.h"
#include "TMC-API/tmc/ic/TMC4361A/TMC4361A.h"
#include "TMC-API/tmc/helpers/API_Header.h"
#include <stdint.h>

static float yAxisPos = 0.0;

void tmc4361A_writeDatagram(int fileD, uint8 address, uint8 x1, uint8 x2, uint8 x3, uint8 x4);
void tmc4361A_writeInt(int fileD, uint8 address, int value);
int tmc4361A_readInt(int fileD, uint8 address);
unsigned char tmc4361A_cover(int fileD, unsigned char data, unsigned char lastTransfer);
void tmc40bit_writeInt(int fileD, uint8 address, int value);
int tmc40bit_readInt(int fileD, uint8 address);

int tmc4361A_init(const char *spiDevice);
int tmc4366A_initiailze(int fileD, const char *displayName);
void tmc4361A_load_position(int fileD, int position);
int tmc4361A_read_position(int fileD);

void tmc4361A_targ(int fileD, 
                   int targ, 
                   int vel,
                   int aMax,
                   int dMax, 
                   int bow1, 
                   int bow2, 
                   int bow3, 
                   int bow4);
                   
void tmc4361A_vel(int fileD,  
                  int vel,
                  uint8_t dir,
                  int aMax,
                  int dMax, 
                  int bow1, 
                  int bow2, 
                  int bow3, 
                  int bow4);
                  
void tmc4361A_close(int fileD);

Resetting
Smoketest passed for TMC-Y
trgt=1000,vel=2,aMax=100,dMax=100,bow1=200,bow2=200,bow3=200,bow4=200
Actual position = 1000
Forward position = 1000
Actual position = 1
Forward position = 1
Actual position = 53
Forward position = 53
Actual position = 106
Forward position = 106
Actual position = 158
Forward position = 158
Actual position = 210
Forward position = 210
Actual position = 262
Forward position = 262
Actual position = 314
Forward position = 314
Actual position = 366
Forward position = 366
Actual position = 418
Forward position = 418
Actual position = 470
Forward position = 470
Actual position = 522
Forward position = 522
Actual position = 574
Forward position = 574
Actual position = 626
Forward position = 626
Actual position = 678
Forward position = 678
Actual position = 730
Forward position = 730
Actual position = 782
Forward position = 782
Actual position = 835
Forward position = 835
Actual position = 887
Forward position = 887
Actual position = 939
Forward position = 939
Actual position = 991
Forward position = 991
Actual position = 1000
Forward position = 1000
Actual position = 1000
Forward position = 1000
Actual position = 1000
Forward position = 1000
Actual position = 1000
Forward position = 1000
trgt=100,vel=2,aMax=100,dMax=100,bow1=200,bow2=200,bow3=200,bow4=200
Actual position = 100
Reverse position = 100
Actual position = 999
Reverse position = 999
Actual position = 947
Reverse position = 947
Actual position = 894
Reverse position = 894
Actual position = 842
Reverse position = 842
Actual position = 790
Reverse position = 790
Actual position = 738
Reverse position = 738
Actual position = 686
Reverse position = 686
Actual position = 634
Reverse position = 634
Actual position = 582
Reverse position = 582
Actual position = 530
Reverse position = 530
Actual position = 478
Reverse position = 478
Actual position = 426
Reverse position = 426
Actual position = 374
Reverse position = 374
Actual position = 322
Reverse position = 322
Actual position = 270
Reverse position = 270
Actual position = 218
Reverse position = 218
Actual position = 166
Reverse position = 166
Actual position = 113
Reverse position = 113
Actual position = 100
Reverse position = 100
Actual position = 100
Reverse position = 100
Actual position = 100
Reverse position = 100
Actual position = 100
Reverse position = 100
Actual position = 100
Reverse position = 100
Actual position = 100
Reverse position = 100
 at the end 
Stopping motors
Closing SPI devices
Closing pigpio

vel=10,dir=1,aMax=100,dMax=100,bow1=200,bow2=200,bow3=200,bow4=200Actual position = 0
Forward position = 0
Actual position = 0
Forward position = 0
Actual position = 99
Forward position = 99
Actual position = 343
Forward position = 343
Actual position = 603
Forward position = 603
Actual position = 864
Forward position = 864
Actual position = 1124
Forward position = 1124
Actual position = 1384
Forward position = 1384
Actual position = 1645
Forward position = 1645
Actual position = 1905
Forward position = 1905
Actual position = 2165
Forward position = 2165
Actual position = 2425
Forward position = 2425
Actual position = 2686
Forward position = 2686
Actual position = 2946
Forward position = 2946
Actual position = 3206
Forward position = 3206
Actual position = 3467
Forward position = 3467
Actual position = 3727
Forward position = 3727
Actual position = 3987
Forward position = 3987
Actual position = 4247
Forward position = 4247
Actual position = 4508
Forward position = 4508
Actual position = 4768
Forward position = 4768
Actual position = 5028
Forward position = 5028
Actual position = 5288
Forward position = 5288
Actual position = 5549
Forward position = 5549
Actual position = 5809
Forward position = 5809
vel=0,dir=1,aMax=100,dMax=100,bow1=200,bow2=200,bow3=200,bow4=200vel=10,dir=0,aMax=100,dMax=100,bow1=200,bow2=200,bow3=200,bow4=200Actual position = 0
Reverse position = 0
Actual position = 6581
Reverse position = 6581
Actual position = 6680
Reverse position = 6680
Actual position = 6923
Reverse position = 6923
Actual position = 7184
Reverse position = 7184
Actual position = 7444
Reverse position = 7444
Actual position = 7704
Reverse position = 7704
Actual position = 7964
Reverse position = 7964
Actual position = 8225
Reverse position = 8225
Actual position = 8485
Reverse position = 8485
Actual position = 8745
Reverse position = 8745
Actual position = 9006
Reverse position = 9006
Actual position = 9266
Reverse position = 9266
Actual position = 9526
Reverse position = 9526
Actual position = 9786
Reverse position = 9786
Actual position = 10047
Reverse position = 10047
Actual position = 10307
Reverse position = 10307
Actual position = 10567
Reverse position = 10567
Actual position = 10827
Reverse position = 10827
Actual position = 11089
Reverse position = 11089
Actual position = 11350
Reverse position = 11350
Actual position = 11611
Reverse position = 11611
Actual position = 11871
Reverse position = 11871
Actual position = 12132
Reverse position = 12132
Actual position = 12393
Reverse position = 12393
vel=0,dir=0,aMax=100,dMax=100,bow1=200,bow2=200,bow3=200,bow4=200 at the end 
Stopping motors
Closing SPI devices
Closing pigpio

It also appears that XACTUAL returns the target position or velocity on hte first read.

Good to hear that you made progress! If you see XACTUAL only counting up, I guess that you did not yet successfully start velocity mode in negative direction. Please be sure to set a negative velocity for VMAX to move in negative direction. Inverting direction using the polarity flag is only for adaptation purpose.

If you see different response with read access to the same register, probably the read procedure misses the dummy read required to transfer the register address, first. The read access is pipelined: The next read access reads data from the previously transmitted address.

If you see different response with read access to the same register, probably the read procedure misses the dummy read required to transfer the register address, first. The read access is pipelined: The next read access reads data from the previously transmitted address.