Hi,
I want to use SPI through direct memory access on Debian, here is what I
got so far:
int enableSPIClock()
{
// map a pointer to the clock control block
pClockControl = (char*)mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED,
memFd, SOC_CM_PER_REGS);
HWREG(pClockControl + CM_PER_SPI1_CLKCTRL) |=
CM_PER_SPI1_CLKCTRL_MODULEMODE_ENABLE;
while(CM_PER_SPI1_CLKCTRL_MODULEMODE_ENABLE != (HWREG(pClockControl +
CM_PER_SPI1_CLKCTRL) & CM_PER_SPI1_CLKCTRL_MODULEMODE));
return 0;
}
int enableSPI()
{
enableSPIClock();
McSPIReset(spi);
McSPICSEnable(spi);
McSPIMasterModeEnable(spi);
// set D0 as output-MOSI , set D1 as input-MISO
McSPIMasterModeConfig(spi, MCSPI_MULTI_CH, MCSPI_TX_RX_MODE,
MCSPI_CH0CONF_DPE0_ENABLED | MCSPI_CH0CONF_DPE1_DISABLED, chNum);
McSPIClkConfig(spi, 48000000, 6000000, chNum, MCSPI_CLK_MODE_0);
McSPIWordLengthSet(spi, MCSPI_WORD_LENGTH(8), chNum);
McSPICSPolarityConfig(spi, MCSPI_CS_POL_LOW, chNum);
McSPITxFIFOConfig(spi, MCSPI_TX_FIFO_ENABLE, chNum);
McSPIRxFIFOConfig(spi, MCSPI_RX_FIFO_ENABLE, chNum);
return 0;
}
int spiWrite(uint8_t *tx, uint32_t length)
{
// cs line is forced to low state.
McSPICSAssert(spi, chNum);
// enable the spi channel for communication.
McSPIChannelEnable(spi, chNum);
while (length > 0)
{
McSPITransmitData(spi, (unsigned int)(*tx++), chNum);
length--;
unsigned int rx = McSPIReceiveData(spi, chNum);
}
// force cs line to the inactive state.
McSPICSDeAssert(spi, chNum);
// Disable the spi channel.
McSPIChannelDisable(spi, chNum);
}
I'm writing to a DAC and every 2nd or 3rd message actually goes through
(gets recognized by the DAC).
The StarterWare site
http://processors.wiki.ti.com/index.php/StarterWare_McSPI references the
*Interrupt
*and *DMA *mode, but I'm not sure if I should use them..?
If anyone has tried a similar thing I'd be more than happy to hear about it.
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