BlueNRG-M2SP module SPI not working as co-processor(replacing the BlueNRG-2N)

[malarab]

Hi everyone,

I designed a first custom PCB using the BlueNRG-2N as a coprocessor, and everything was working fine, I was able to control it with my main MCU over SPI without any issue.

Recently, I made a new version of the board where I replaced the BlueNRG-2N with the BlueNRG-M2SP module. I flashed it with the DTM firmware (BLUENRG-M2SP_DTM_SPI.hex) because I want to use it as a coprocessor.

I’m using exactly the same software as before for my main mcu (which should work), but now it doesn’t work at all : I don’t receive any data on the SPI MISO line from the BLE module.

I’ve attached both the old (working) and new designs. Since the firmware works with the BlueNRG-2N, I assume the issue is hardware-related. What could be wrong in my new design? Or what changes are required for the software ?

Also, I have a couple of additional questions:

1- There are multiple DTM firmware versions available (e.g. BlueNRG-M2SA_M2SP_DTM_Stack_v2.1c, v2.1e, and several others in the BlueNRG-1_2 DK 3.2.3)... Which one should I use for SPI coprocessor mode?

2- I was never able to connect to the BlueNRG-M2SP using the BlueNRG-1 ST-Link Utility, but it works fine with the RF Flasher Utility. Is this normal, or could it indicate a problem with my hardware?

Thank you,

Sincerely

[Laurent LOUAZON]

Hello,

Few comments here.
1) I agree an application FW running with BlueNRG-2N over SPI should be functional as well if using BlueNRG-M2 with same SPI interface.

However

2) BlueNRG-2N get the specific features to select UART or SPI interface through  DIO12.
This is not true with BlueNRG-M2. 
So handling DIO12 is useless with BlueNRG-M2. Customer should select UART or SPI interface and flash proper DTM FW version

3) You should flash a DTM SPI M2SP image with BlueNRG-M2SP (and logically DTM SPI M2SA image with BlueNRG-M2SA)
Internally, BlueNRG-M2SP is not having integrated SMPS and neither 32kHz Xtal.
So it is important to flash proper image (DTM_SPI_M2SP) from BlueNRG-1_2 DK 3.2.3\Firmware\BLE_Examples\DTM_M2SA_M2SP\BlueNRG-2

Regards
Laurent

[Imen.D]

Hi @malarab,

Just checking in to see if your issue has been resolved.

If your questions are answered by Laurent, please close this topic by choosing "Accept as solution".

If you have further questions or still need support, do not hesitate to return to the Community. You can create a new thread or continue this one if your question relates to the same initial topic.

[malarab]

Hi Laurent,

I confirm that i use the ST\BlueNRG-1_2 DK 3.2.3\Firmware\BLE_Examples\DTM_M2SA_M2SP\BlueNRG-2\DTM_SPI_M2SP.bin

the flashing process success

Here a screenshot

However, I noticed that the input data register read by the microcontroller on the interrupt pin is always high. In the previous setup with the BlueNRG-2N, the signal was low and went high when an interrupt was triggered. In this current version using the BlueNRG-M2 module, the pin remains constantly high, so no interrupt is being detected.

Even after enabling the microcontroller’s internal pull-down or adding an external 10 kΩ pull-down resistor, the pin still never goes low.

Do you have any idea what could cause this behavior, and what would be the best things to check to diagnose the problem?

Thank you,

Sincerely.

[malarab]

Just for your information, to have a complete overview, on the same circuit, I also upgraded the main microcontroller from the STM32WL55CC to the STM32WL5MOC. I adjusted the necessary source code for the microcontroller reference, but continued to use the same application code and the same pin configuration, which was working before.

All other element on the circuite after upgrade are working correctly (subghz, external flash, sensors, serial ports, IO LED and Buttons) ... so i suppose that the upgrade went good.

Also the same SPI port used with the BlueNRG-M2 module is used with an external eeprom, and i it work with it. which mean that the SPI config is working well.