AFE031: SPI Communication Problem

Hi Mani,

Udhayakumar Mani said:

If there is any example application note is available with access registers please give us.

We have many customers who use 3rd party MCUs to communicate with AFE031 in their PLC controller product. It is likely that the SPI protocol is not configured properly.  

SPI has two modes, see see the AFE031's datasheet, also the link below. 

Please write a small program and test his read/write code via  AFE031's registers via SPI protocol. I think that the SPI protocol is specific to TI and I recalled that SPI code implementation may be slightly different from others.    

There are some differences between MCU and DSP processors to setup the SPI configurations.  In the link below, there are some instructions in how to configure AFE031. Although this is specific to C2000 DSP processor, the overall procedure should be still correct for MCU processor. 

https://www.ti.com/lit/an/sprac94d/sprac94d.pdf?ts=1705429676956

If you have other questions, please let us know. 

Best,

Raymond

Hi Raymond Zhang1,

Thanks for your reply,

Yes, I was already saw those details. I was configured SPI as per the data sheet. But I am having a problem.

But there is a only different, which means datasheet have a 16 bit transfer SPI communication but I having a MCU can transfer 8 bit  SPI.

1).Did you notice any configuration problem in my above details ?

2).Is we need to write a register before we read from a register , that is necessary or not?

3).can you tell what are the possibilities when read registers value as given 255.

Hi Mani, 

AFE031's register is only supported in 16 bit word size (the registers are designed for 16 bit access only.). I am afraid that you have to configure the SPI communication in 16 bit. You have to find 16 bit MCU to communicate with the part.   

If you have other questions, please let us know. 

Best,

Raymond

Hi Raymond Zhang1,

Ok, I understand.

Can you tell about what are supported frequency levels are in SPI communication ?

I seen only Tx and Rx frequency levels in datasheet , can you tell about. or any frequency level is applicable for SPI communication ah ?

Hi Mani, 

Udhayakumar Mani said:

Can you tell about what are supported frequency levels are in SPI communication ?

The SPI needs to communicates > 1.5MHz, if you are using the onboard DAC feature. 

If you are using PWM mode to send the GPIO signals to AFE031, then it does not require the higher speed SPI data rate. 

If you have other questions, please let me know. 

Best,

Raymond

Hi @Raymond Zhang1,

I have an a doubt

1. Is it necessary to give a voltage supply to PA_VS1 & PA_VS2 Pins whether I try to read in data registers and command registers ?

I found that details about to read registers in AFE031 like below for before start SPI to read data / command registers

1. SD Pin -> pulldown
2. DAC pin -> pulldown (Access only on command and data registers)

3. AVDD -> +3.3V
4. DVDD -> +3.3V

Is anything I missing or need to verify before start SPI communication to read the registers ?

Hi Mani,

Udhayakumar Mani said:

1. Is it necessary to give a voltage supply to PA_VS1 & PA_VS2 Pins whether I try to read in data registers and command registers ?

Yes, it may be necessary. The PA_VS1/PA_VS2 establish the IC's internal bias voltage, as seen in the diagram below. It depends on which internal analog and/or digital block you are trying to access, the internal bias REF1 and REF2 should be present, which are used to bias other blocks inside of the IC, such as Control Register and other internal blocks. Otherwise, it may not have the proper bias voltage to work properly. 

You do not need to apply the rated 26V to AFE031. If PA_VS1/PA_VS2 pins are connected to 10V to 16Vdc should do, I think that it should work. For instance, the following DAC signal depends on AVDD supply rail; the digital signal may depends on DVDD supply, rail, but the internal op amp and analog circuitries are powered by REF1 and REF2 bias voltage, which are not clearly specified. So it is necessary to connect to PA_VS1/PA_VS2 pins (no load is necessary, if you want to talk to the part). 

If you have other questions, please let me know. 

Best,

Raymond

Hi @Raymond Zhang1,

Thanks for your prompt response.

You are gave more information about AFE031 Registers Read and Write via SPI communication.

Now I have a availability problem of 16bit SPI communication MCU and PA supply circuit once it will be ready and I will check and update feedback to you. 

Thanks,

Hi Mani,

Ok, if you have any questions, please let me know. We have many customers who are using their preferred MCU to interface with AFE031's SPI, register read/write and IC control. So the 3rd party MCU and hardware in communicating with the digital part of SPI are not the issues.

Best,

Raymond