topic Re: SPI RXDATA always 0 in i.MX Processors

SPI RXDATA always 0

muthuswamydiksh — Fri, 25 Apr 2014 15:43:21 GMT

I am reading only 0x00 in ECSPI RXDATA register.

I am using iMX6 with BSP 4.1.0. Kernel version 3.0.35.

I am using spidev4.2 as master and mode =0.

I can see that SCK and MOSI are sending out correct data.

I can also see correct data in MISO line.

But the RXDATA register always reads 0. I put a printk in spi_imx_buf_rx_##type in spi_imx.c file.

#define MXC_SPI_BUF_RX(type) \

static void spi_imx_buf_rx_##type(struct spi_imx_data *spi_imx) \

{ \

unsigned int val = readl(spi_imx->base + MXC_CSPIRXDATA); \

printk(KERN_INFO"%s: %s: %d: rxdata = %u\n", __FILE__, __func__, __LINE__, val); \ \

if (spi_imx->rx_buf) { \

*(type *)spi_imx->rx_buf = val; \

spi_imx->rx_buf += sizeof(type); \

} \

}

Val always prints 0.

I am not able to figure out why.

I am send two bytes. 1^st is command and 2^nd byte is dummy(0x00). On sending the second byte I can see the correct response on MISO line but it doesn’t reflect in RXDATA register.

I am doing 16 bits-per-word burst transfer. Since one command-response sequence takes 2 bytes.

I did multiple 16bpw transfer. But still I read only 0x00 in RXDATA register.

Request some help for me.

Thanks!

Re: SPI RXDATA always 0

muthuswamydiksh — Sun, 27 Apr 2014 10:12:14 GMT

I have to complete it asap. Request your help.

Re: SPI RXDATA always 0

igorpadykov — Tue, 29 Apr 2014 08:59:29 GMT

Hi Muthuswamy

actually there many i.MX6 processors: i.MXDQ,DLS,SL -

which one are you using ? Had you chance to test on Freescale

Reference boards: Sabre SDP/SDB/AI ?

Had you checked IOMUX settings, what pads were used, had

you checked if Daisy Chain involved in ECSPI input path ?

Re: SPI RXDATA always 0

muthuswamydiksh — Fri, 02 May 2014 05:16:32 GMT

A resistor was not populated. That was causing the MISO line give correct output, but when looked closely, it could be observed that the amplitude of the data was ~1V. SO, the uC would read a 0 always. Solved.

chipexpert, thanks for your suggestions.

Re: SPI RXDATA always 0

wenjingwang — Sat, 11 Oct 2014 08:26:52 GMT

I have the same issue on my IMX6DL sabresd board, my question link is :

https://community.freescale.com/thread/332450dd

can any one help me about this issue? thanks.