Problems with SPI protocol between my MCU and LDC1000.

Sergio Delfin

Other Parts Discussed in Thread: LDC1000EVM

Hello there!

I have an evaluation kit LDC1000EVM, with the portion of the EVM (just LDC chip and PCB coil) I have been trying to connect it directly via SPI protocol with a different MCU and I have not been successful. I used a fuction generator like an external source clock at 6 MHz. I hold a pic where it shows the waves forms of the interface. I don't know what is wrong. I don't have achieved the communication when I send 0x21 and 0x22 to obtain the proximity data. I set the POWER MODE to 0 before setting other registers and the parameters of the pcb coil are equal like the software GUI shows it, the VIO voltage and the VDD are 5 V.

I will be gratefull for any help you can provide.

Sergio D.

over 11 years ago

0 Charles Cheung* over 11 years ago

TI__Intellectual 2790 points

Hi Sergio,

Have you tried reading other registers successfully or is it only 0x21/0x22?

Thanks,

0 Sergio Delfin over 11 years ago in reply to Charles Cheung*

Prodigy 30 points

Hi Charles,

I tried reading registers without success.

Thanks.

Sergio.

0 Charles Cheung* over 11 years ago in reply to Sergio Delfin

TI__Intellectual 2790 points

Hi Sergio,

Thanks for the trace. It seems that you are not reading any data since the clock does not continue beyond 8 bits (CSB goes high ending the transaction; you are simply writing the register address but not reading anything). Please see this trace for an example of what you want:

SPI is a full duplex protocol so in most microcontroller implementations you would have to "write" 0x00 twice to read 2 bytes of data out (in this case Rp).

Thanks,

0 Sergio Delfin over 11 years ago in reply to Charles Cheung*

Prodigy 30 points

Hi Charles!!!

I tried to implement your suggestion, starting with the trace shown above, I modified the code of the MCU to follow the sequence of reading registers, and it resulted in a good performance. I can not control the space between "block of clocks", the reason, I think, it ocourrs inherently to the process of the MCU, even so I can read registers of proximity data.

It was an excelent suggestion.

Thanks a lot.

Regards.

Sergio D.

0 Charles Cheung* over 11 years ago in reply to Sergio Delfin

TI__Intellectual 2790 points

Glad you got it working!

Let me know how we can further assist.

Thanks,

Sensors

Sensors forum

Problems with SPI protocol between my MCU and LDC1000.