Posted on May 17, 2011 at 10:20Hi there
My motor turns! I could manage the chip by lowering the supply voltage from 24V to 12V. Now the chip doesn't get too hot and the motor turns exactly where I want him to turn. But I really doubt the chip could handle a 3A stepper... Perhaps with an improved print layout including heat sink and fan. But surely not on the evaluation board.
Also my settings were not really ''L6470-friendly'' so I had to raise the acceleration value up to 2000 and lower the maximum speed to 120. Tonight I'm going to do a long duration test and I hope the chip will still work tomorrow morning :)
In conclusion, the chip doesn't seem to by ready to market and it's documentation is not really entire. I hope there will be a real application note soon... As you said AN3103 is not an application note at all.
Here is my code to send and receive SPI data:
BYTE readSPI (void)
{
int bitNr = 7; //counter variable
BYTE returnByte = 0x00; //return byte
BYTE masks[8] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80}; //bit masks
BOOL pValue = 0; //MISO value
U2C_SingleIoWrite(m_spiHandle,SPI_MOSI,0);
//MOSI = 0, that looks like a NOP-command for the chip
U2C_SingleIoWrite(m_spiHandle,SPI_SS,0); //CS = 0
for (bitNr=7; bitNr>=0; bitNr--) //do it for each bit
{
U2C_SingleIoWrite(m_spiHandle,SPI_CLK,0); //clock = 0
U2C_SingleIoWrite(m_spiHandle,SPI_CLK,1); //clock = 1
U2C_SingleIoRead(m_spiHandle,SPI_MISO,&pValue); //read bit on MISO
pValue > 0 ? returnByte = (returnByte | masks[bitNr]) : NULL;
//if read bit is 1, set bit in return byte
}
U2C_SingleIoWrite(m_spiHandle,SPI_SS,1); //CS = 1
return returnByte; //return the byte read
}
void writeSPI( BYTE data )
{
int bitNr = 7; //counter variable
BYTE masks[8] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80}; //bit masks
U2C_SingleIoWrite(m_spiHandle,SPI_SS,0); //Chip Select = 0
for (bitNr=7; bitNr>=0; bitNr--) //do it once for each bit
{
U2C_SingleIoWrite(m_spiHandle,SPI_CLK,0); //clock = 0
U2C_SingleIoWrite(m_spiHandle,SPI_MOSI,(data&masks[bitNr])>>bitNr);
//write bit to MOSI-pin
U2C_SingleIoWrite(m_spiHandle,SPI_CLK,1); //clock = 1
}
U2C_SingleIoWrite(m_spiHandle,SPI_SS,1);
//after the byte is transmitted, raise CS
}
