Max Freq Input with Step/Dir

[morbak]

Hi,

I drive a TMC249 with µC via SPI.
µC Freq is 10Mhz with internal PLL(x4) [PIC18F4582]

I converting Step/Dir inputs to SPI (16bits) and I want to know what is the max Step frequencie input and what is themotor's max rotation speed ?

I've noticed when i comment the SPI reading of TMC249's ErrorBits , the motor move, but when i uncomment the SPI reading the motor don't move and make strange noise even a very low freq step input:

Code: Select all

            WriteSPI(BYTE1(SPIData));
//           BYTE1(ErrorBits)=ReadSPI();

            WriteSPI(BYTE0(SPIData));
 //         BYTE0(ErrorBits)=ReadSPI();

i my program , there an interrupt on every step input to count the pulse. and a main loop to extract the value to the sin table and send the 2 byte over SPI, it's very light.


Thx, have a good WE

[TRINAMIC_BD]

Hello,
in order to assess the max. possible frequency, you must make sure, that the interrupt procedure is ended before the next step comes. You could measure with a scope, by setting an output pin during the runtime of the procedure which must run for every step. In order to speed up, you could skip every second step at high input frequency.