nRF51 dk 16 bit spi runtime error

RE: nRF51 dk 16 bit spi runtime error

ksrc — Wed, 13 Jul 2016 09:14:18 GMT

Hi Martin, Sorry about this question being so late is there a way for me to basically let the ss run for 16 frames using interrupts to decide when it goes from high to low? I don't need to send all 16 bits over bluetooth but i just need to figure out how to get the data onto the nrf and then afterwards i can figure out what bits i want to send via bluetooth.

Thank you again.

RE: nRF51 dk 16 bit spi runtime error

MartinBL — Wed, 01 Jun 2016 10:30:46 GMT

Unfortunately not.

RE: nRF51 dk 16 bit spi runtime error

ksrc — Wed, 01 Jun 2016 09:54:22 GMT

Thanks for the help again. I already looked but there are no Nordic modules that support 16 bit frames correct?

RE: nRF51 dk 16 bit spi runtime error

MartinBL — Tue, 31 May 2016 08:23:38 GMT

As mentioned, I'm not very familiar with mbed, but if you look in "/targets/hal/TARGET_NORDIC/TARGET_MCU_NRF51822/" in the repository you linked to you will find spi_api.c. This file contains the function definitions that are actually being used. In the function spi_format() you will find the following check:

if (bits != 8) {
    error("Only 8bits SPI supported");
}

prohibiting you from using any other bit widths than 8 bits.

The SPI library in mbed tries to cover many MCUs, but not all MCUs have similar SPI capabilities. Some of them support various bit widths, but unfortunately nRF51 is one of those who don't. I was not able to find this documented in the mbed drivers, but as you can see in the function definition in spi_format() you will get an error if you use something else than 8 bit.

RE: nRF51 dk 16 bit spi runtime error

ksrc — Tue, 31 May 2016 07:13:37 GMT

Hi Martin, Thanks again for replying. I really appreciate your help. I also noticed that if I set it to bit widths smaller than 8 as well I get a run time error. Here's the driver I'm using I'm looking at the SPI.h line 83 and there's a commented line saying 4-16 should work. I saw this at one point before which is the reason why I thought I shouldn't have any problems.

RE: nRF51 dk 16 bit spi runtime error

MartinBL — Mon, 30 May 2016 09:20:37 GMT

Do you have a link to the driver? Could it be that the nRF51 mbed SPI driver does not support 16-bits format? For example I found this driver and it returns an error if you try to use any other bit widths than 8 bits.

RE: nRF51 dk 16 bit spi runtime error

ksrc — Sun, 29 May 2016 11:28:50 GMT

Hi Martin , Thanks for the reply. I'm wondering when you mean the nRF51 only supports 8 bit you are talking about the Bluetooth? I should still be able to send 16bit frames to the board right? What I have coming from the FPGA is in 16 bit but I really only need to broadcast a certain portion of that 16 bits. This should be possible right? Sorry for the vague question.

RE: nRF51 dk 16 bit spi runtime error

MartinBL — Tue, 24 May 2016 13:50:55 GMT

Hi, sorry for the delayed response. I'm not familiar with the mbed SPI drivers, but are you trying to send 16-bit frames? The nRF51 only supports 8 bit.