TIDA-080004: TMS320F28023 has no SPI response signal

Hi Julia,

Does the customer have access to the following SPI documentation guides?

DLPU061_Piccolo_SW_Guide_201803.pdf

DLPU057_Piccolo_SPI_Command_Guide_201803.pdf

In the SPI command guide it should have examples of commands and responses like this.

Thanks,

Alex Chan

Hi Alex,

Customer have tested the TIDA-080004 code and they found F28023's output is different.

According to https://www.ti.com/lit/ug/dlpu057a/dlpu057a.pdf , in the case of the figure below, F28023 SPISOMI output should be 0xFF........0xFF, 0x01. But SPISOMI in the waveform captured by the customer is 0xFF........0xFF, 0xFF. You can also see this in following attached video. SPISIMO's signal is the same as following picture's Host(Master), SPISOMI's signal is not the same as following picture's Piccolo(Slave).

It seems that Piccolo missed the "Response Byte" 0x10, but I can't find any explanation about this response bit, when is it generated and what could be the reason for missing it?

For your reference,customer now are using software simulate spi, and it may cause a delay between SPICLK(green) and SPI_ENABLE(yellow).

And customer's code is programmed from flash memory.

Could you please help analyze the reason for this? Thanks!

BR

Julia

Hi Julia,

I am looking into this. Did the customer build their own board or do they have our EVM or electronics boards?

One thing that can be tried is in the DLPC120 Control Program under utilities there is Piccolo SPI command and then a SPI command log. If the customer purchased our EVM or can hook up and communicate with the DLPC120 Control Program with their system they can do this check.

The example below was sending a backlight value of 65535.

Then in the SPI command log tab you can decode and see the response. In this case I see a Success and got a 0x01 as a response.

Thanks,

Alex Chan

Hi Alex,

Customer use TI EVM now. Customer can send commands through the DLPC120 Control Program to realize backlight adjustment, and there is a response signal on C2000. However, customer think that this can only prove that the C2000's SPI is working, which does not solve the problem that the customer simulates SPI through software without a response signal. Customer is using IO to simulate SPI, not using hardware SPI.

So customer want to know why SPI have no response signal when using SW simulate SPI. Should a delay between SPICLK(green) and SPI_ENABLE(yellow) will cause it? 

BR

Julia