Other Parts Discussed in Thread: SYSCONFIG
Dear all,
I am working with SPI bus. I already used a lot spidev and it seems to work really good. Now I would like to go ahead and try to set directly registers to use the SPI bus. I decided to short MOSI and MISO to check data and to use the AM335xx as master. I am not working at high frequency.
This is my main settings:
*(data + SPI_SYSCONFIG) |= 0x3;
*(data + SPI_IRQENABLE) = 0x0;
*(data + SPI_SYST) = 0x80;
*(data + SPI_MODULECTRL) = 0x01;
*(data + SPI_CH1CONF) = 0x00190FF0;
If a try to have a single write doing:
*(data + SPI_CH1CTRL ) = 0x1;
*(data + SPI_TX1 ) = data_to_sent;
*(data + SPI_CH1CTRL ) = 0x0;
it works as I want: I can read on MISO data sent by MOSI.
When I try to have a loop, such as:
for(i = 0; i < N; i++){
*(data + SPI_CH1CTRL ) = 0x1;
*(data + SPI_TX1 ) = data_to_sent[i];
*(data + SPI_CH1CTRL ) = 0x0;
}
data on MISO are different from data on MOSI; if I try to put a sleep in the for cycle, it works again.
for(i = 0; i < N; i++){
*(data + SPI_CH1CTRL ) = 0x1;
*(data + SPI_TX1 ) = data_to_sent[i];
*(data + SPI_CH1CTRL ) = 0x0;
sleep(1);
}
It seems that, for some reason that I do not understand at all, MISO does not follows MOSI in a for loop without that sleep. Am I missing something (maybe there is a wrong setting on a register or I do not reset something else..)?
Any help is really really appreciate.
Regards.
Alberto
