How: Serial communication between the BLE module on a nRF52 board and a off-board MCU

[ulyssis]

Hi there.
I have a project, where we are considering to use a non-Nordic mcu (I call it off-board MCU) and Nordic BLE module.

As the first step, I have run some BLE samples to relize the connection between the Nordic evluation board with an APP on a phone via BLE. in Other words, it is

Nordic MCU on board <---serial---> BLE <---bluetooth---> APP

the next step is to replace the 'MCU on eval board' with the the off-board MCU we are using. My question is how to connect the off-board MCU with the BLE module on the eval board.

The expected connection looks like:

Off-board MCU <---serial---> BLE <---bluetooth---> APP

There is a UART port on the off-board MCU, which has 3 pins. do I only need to find out the 3 (or 2?) pins on the eval. board to connect?

In the "User Guide" P8, it reads that user should disable "Dynamic Hardware Flow Control (HWFC) handling" in order to use the P0.05 and P0.07, by sending DTR signals, but i didn't find much information about DTR and don't know how to send out it to the interface MCU on the eval. board.

There is a simlar topic:
About hardware flow control - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

but the answer is not available.

I also found another related thread , but I am not sure that is exactly the same problem.

Connecting UART Data to development board PCA10040 - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

thanks!

[Menon]

Hello,

I am not sure if I understand you correctly. I guess you are looking for serial communication between the two MCUs. There is a tutorial to explain serial communication on Nordic chips. If this is not what you are trying to achieve, could you please elaborate a bit more, like how you want to connect two MCUs? Which protocol are you planning to use? Which Nordic chip and which SDK version are you using here?

Kind Regards,

Abhijith

[ulyssis]

Hi Abhijith, thanks for your response.
No, I am trying to connect a off-board MCU with the BLE module (the module around nrf52832 on the eval board) on the eveluation board.

Normally on the evtl board 52832, the on-board MCU (interface MCU) communicates with the BLE module, but now I am trying to connect the BLE module with a seperate MCU via UART.

[ulyssis]

what I am looking for is a way to "cut" the uart connection between the BLE module and the interface MCU, then let the BLE modle communicate with the off-board MCU with two (?) jumper cables.

in the user guide there is Dynamic hardware flow control handing, but I am not sure whether it is used to "re-route" the uart.

I also have a silly easy question: isnt it enough only to use RTX and CTX for UART communication? I don't understand why there are also CTS and RTS invloved.

very appreciate for any hints.