Test SPI Slave

Hi Mike,

Able to see transitions on SPI bus while you access the SPI ?

Are you following correct sequence for initializing the OLED like configuring mode (128*32) etc.,

Also try to use the following app code located in linux source code to configure & initialize the OLED.

<linux source > /Documentation/spi/spidev_test.c

Hi Titus,

I am not sure what you meant by 'transitions' ?
How do I verify that command is sent to SPI slave ?

Thanks And Regards,
Mike

Hi Mike,

I am not sure what you meant by 'transitions' ?
How do I verify that command is sent to SPI slave ?

When you probe through CRO, able to see any changes of CLOCK and DATA lines of SPI bus while you transfer the SPI data to OLED ?

Hi Titus,

As per your suggestion I looked the clock and data lines its always low. Any pointers on how to proceed further would be helpful.

Thanks And Regards,
Mike

Hi Mike,

Please make sure that you have completed proper pinmuxing to enable particular SPI instance peripheral. (say ex SPI1)

What processor are you using ?

How about CHIP SELECT (CS) signal ?

Hi Titus,

The slave is connected to SPI1, I am using dm8148. the CS signal is low (only one slave on SPI1)

Thanks And Regards,
Mike

Hi Titus,

Is there a way in which the spi can be tested in GPIO mode to test the signal ?

Thanks And Regards,
Mike

Hi Titus,

I am using the TI provided linux, in which all the SPI1-4 are initalized, my SSD1306 oled is connected to SPI1, I have written a driver based on ssd1306 datasheet, and added the following:-

{
.modalias = "ssd1306xx",
.irq = -1,
.max_speed_hz = 25000000,
.bus_num = 2,
.chip_select = 0,
.mode = SPI_MODE_0,
},

I am not sure how to determine the max_speed_hz and mode which I have just put randomly.

Thanks And Regards,
Mike

Try  to modify like below.

{
.modalias = "ssd1306xx",
.irq = -1,
.max_speed_hz = 25000000,          //Check the OLED data sheet for max SPI frequency supported.
.bus_num = 1,             //SPI1
.chip_select = 0,         //CS0 ? : Are you connected CS0 to SPI OLED display ?
.mode = SPI_MODE_0,
},

Now check the data lines of SPI through CRO and able to see the clock in SPI CLOCK line in 25MHz ?

Hi Titus,

Can you please point me on how to determine chip select from data sheet, In the schematic it just says SPI nothing about cs0.

Thanks And Regards,
MIke

How did you connect the SPI 1' s CS pin to OLED display ?
That CS pin no should mentioned in board file while you init the platform code.
If you are not sure, please refer to the schematics of your board.
Else contact your hw team.

Hi Titus,

I looked at the schematic and it is cs-0, Ideally if you are not writing to SPI will the CS be low/high ? and clk pin aswell ?

Thanks And Regards,

Mike