I built a print with hardware exactly as shown in figure 3.2 (page 12) of the datasheet TMC2226 with MS1=MS2=LOW , ENN=STEP=DIR= HIGH and SPREAD and
STDBY are left open. Vref to 5VOUT: 6K8 ohm. VS not connected yet to avoid overcurrent.
On the UART pin I sent according to instructions on pages 20 ,15 and 53 of the datasheet TMC2226:
||UCHAR instructions[8];|
||instructions[0] = B10100000; //synchronisation|
||instructions[1] = B00000000; //slave adres
||instructions[2] = B00000001; //register adres 00(GCONF)
||instructions[3] = 0;|
||instructions[4] = 0;|
||instructions[5] = 0;|
||instructions[6] = B01000000; //lowest databyte; intern resistor|
||swuart_calcCRC (instructions,(byte)8); //(checksum calculation function copied from datasheet) generates instructions[7]
It was sent to the TMC pin UARTwith|
for (i=0; i<8; i++) {
instructionline = instructions[i];
digitalWrite (UART_TCM2226, 0); //start byte
delayMicroseconds (5);
for (j=0; j<8; j++) {
digitalWrite (UART_TCM2226, (instructionline& 0x80)? 1 : 0);
instructionline = instructionline << 1;
delayMicroseconds (5);
}
digitalWrite (UART_TCM2226, 1); //eind byte
delayMicroseconds (5);
A logic analyser, showed that the message is sent exactly as intended, but unfortunately a copy of it cannot be copied here.
I expect a drop of the voltage on pin 21 (VREF) to a constant value of about .3V after a succesfull instruction.
This however keeps drifting between about 1 and 3 Volts.
Question now is: What might have gone wrong or do I have a wrong expectation?
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