AFE031: how to read registers

Hi Chao,

I replied how to access AFE031's registers a while ago. Please read the thread and if you have any additional questions, please let me know. I will be happy to help you to resolve the issue. 

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/925688/afe031-afe031-spi-control-register-question/3443408?tisearch=e2e-sitesearch&keymatch=afe031%252520register#3443408

Best,

Raymond

Hi Raymond,

Thanks for the reply.

I have read through the thread you mentioned, you gave some advice on reg write, but there is no info on reg read. At the moment, we can do reg write correctly (because Tx, Rx, ZC, PA, ETx, etc. are all working properly), please could you have a further look at the bottom-half of the message I provided, and confirm whether the following statement is correct or not:

SPI writes 0x8A00 for reading reg 0xA

this is to read DIE_ID, the default value is 0x01, but I got 0x89, which is the COMMAND REGISTER value in  the second last write to SPI.

If the above statement is wrong, then what is the correct sequence for a reg read?

Best Regards

Chao

Hi Chao,

Per the AFE030's datasheet, the R/W bit 15 is required to be configured as 1 = Read and the address 0Ah has default 01h as the Die ID. 

If you are able to write to the register, you should be able to read from the register. You are required to select one of SPI 0,0 or 1,1 Mode of operation.  In AFE030, it is all detected automatically, I recall (In TI's other ICs, the SPI modes may be configured via hardware pins).

Let me know if this is resolved your issues. Please check with our sample code and see how it is implemented in the program. 

Best,

Raymond

Hi Raymond,

Agree, if one can write to registers correctly, then should be able to read from them correctly. We deliberately enabled/disabled ETx block and ZC block to test the SPI write funcionality, this quarantees our programming for SPI writes are all correct. However, all register reads were incorrect.

We use an NXP MCU as the host, due to the different descriptions on SPI communication in AFE030 datasheet and the MCU, we had to try all MCU's possible SPI configurations and found a way of correctly doing the SPI communication, so we donot know which mode we are using for the SPI communication.

In AFE030 datasheet, it only gives 3 modes: SPI 0,0 or 1,1, or standalone, and there is no further description on the 3 modes, especially for register read, there is only one timing diagram for standalone mode. Does this mean one can only use the standalone mode to perform a register read ?

Best Regards

Chao

Hi Chao,

Since you are using NXP MCU, please verify the SPI timing requirements for AFE03x part. It is required to select and meet either SPI Mode 0,0 or Mode 1,1 timing diagram for the proper Read or Write sequence in AFE03x. Please make sure that TI's SPI mode operation is matching with NXP's mode of operation, which modes of operation may be defined differently between two companies. 

Below is an example how Read and Write is executed in TI's SPI Protocol. Enclosed is a video about how TI's SPI protocol and timing are defined. 

https://training.ti.com/ti-precision-labs-adcs-spi-serial-modes-clock-data?context=1139747-1140267-1128375-1146616-1148195

https://training.ti.com/ti-precision-labs-adcs-spi-setup-hold-delay?context=1139747-1140267-1128375-1146616-1148207

I am not software engineer. If you are still having issues, you may also C2000 MCU engineers about our SPI operation. Please let me know. 

Best,

Raymond 

Hi Raymond ,

Thanks so much for this reply. Your message (especially the first screenshot) is the first text description I have ever seen on AFE03x's SPI communication. It talks the same language as NXP's MCU. Your screenshots should be put into the AFE03x's datasheet. If TI did this, we (I believe it includes a lot of people who try to use AFE03x) should have avoided wasting lots of time on evaluation period.

Now I have a question on the standalone mode, what is this? Is it possible to use CPOL/CPHA or something similar to give some description on it. This is the only working mode mentioned by AFE03x's datasheet in a timing diagram.

Regards

Chao

Hi Chao,

Your comments are valid, however, I think that you are taking the AFE03x's development in a wrong approach. You should have contacted our local FAE in China for support, which they will provide you with a free EVM kit for your development. The EVM + TI's DSP processor consists of ready to run sample codes, which you will save a lot of time instead of trying different things in interfacing with SPI interface. I understood that your frustration. 

I know that you prefer to use your familiar MCU processor (ARM) for the application. TI processor in this class are based on DSP technology.  At least you can try deciphering our AFE03x driver (afe031_config and hal files) if you'd like, which is in the C2000WARE installation directory below. Once you understand the AFE03x's interfaces, you may switch to something you prefer (cost reasons, familiarity or others), though we would like our customers to use our products. 

(Note that C2000 devices are 16-bit (word) addressable, not byte like ARM cores, and require left-shifting data).

SPI interface is not a standardized serial communication, I recalled. Each company has slight different timing and protocols and other prioritized features, though general interface features may be similar. I am hardware support engineers now, though I programmed SPI interfaces a long time ago. I will help you as much as I can, but certain things you may have to contact our C2000 software engineers for support via E2E forum. 

https://www.ti.com/lit/an/sprac94c/sprac94c.pdf?ts=1640187837384&ref_url=https%253A%252F%252Fwww.ti.com%252Fsitesearch%252Fdocs%252Funiversalsearch.tsp%253FlangPref%253Den-US%2526searchTerm%253Dboostxl%2Bafe031%2Bf28004x%2Bdacmode%2526nr%253D1

https://www.ti.com/licreg/docs/swlicexportcontrol.tsp?form_id=268791&prod_no=C2000-AFE031_FSK_RX_SOURCE&ref_url=c2000

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1009512/launchxl-f280049c-launchxl-f280049c-need-help-to-combine-tx-and-rx-solution-with-plc-example-code

If you go to the bottom of the following link, you should find additional relevant processors (low cost TMS320F280025C and TMS320F28004x)

and sample code for AFE03x PLC application. 

https://www.ti.com/product/AFE031#tech-docs

Now I have a question on the standalone mode, what is this?

The Stand-Alone mode is only applicable for AFE03x's registers (e.g. troubleshoot or debugging etc.). I was not involved when the products were put together. Some of the information is not well informed. It is likely that it is assumed that customer will use C2000 DSP processor and AFE03x EVM + DSP sample codes were provided 

If you want to know more, please ask it via E2E Forum via C2000 support team. 

Best,

Raymond

Hi Chao,

Duplicated reply.  

Best,

Raymond