Open
Description
When you mount/unmount an SD with following config:
"sd.SPI_CS": "SD_CS",
"sd.SPI_MOSI": "SD_MOSI",
"sd.SPI_MISO": "SD_MISO",
"sd.SPI_CLK": "SD_CLK",
"sd.TRX_FREQUENCY": 40000000,
/**** SD card pins ****/ //SPI2
SD_MOSI = PB_15,
SD_MISO = PB_14,
SD_CLK = PB_13,
SD_CS = PB_12,
SDBlockDevice sd;
FATFileSystem fs("fs");
fs.mount(&sd);
fs.unmount();
And you use SPIF with this config:
"spif-driver.SPI_CS": "SPIF_CS",
"spif-driver.SPI_MOSI": "SPIF_MOSI",
"spif-driver.SPI_MISO": "SPIF_MISO",
"spif-driver.SPI_CLK": "SPIF_CLK",
"spif-driver.SPI_FREQ": 40000000
/**** SPIF pins ****/ //SPI3
SPIF_MOSI = PC_12,
SPIF_MISO = PC_11,
SPIF_CLK = PC_10,
SPIF_CS = PA_15_ALT0,
And you use legacy code which is not using HW chipselect:
_select(true); // set CS 0
_spiwrite(0x80); // RS:1 (Cmd/Status), RW:0 (Write)
_spiwrite(command);
if (data <= 0xFF) { // only if in the valid range
_spiwrite(0x00);
_spiwrite(data);
}
_select(false); // set CS 1
During the first SPI cycle there is a unwanted dip in the clock which misconfigures the slave device. This has as result that all the following data that you want to read will be read as zero.
If you remove the lines:
// fs.mount(&sd);
// fs.unmount();
Then you have a correct start cycle and the SPI slave is readout correctly:
