AT-Commands from ESP32 to Fanstel BC805M not working

[Fabchick]

Hello DevZone,

I want to send a simple AT-Command like: AT\r\n from the ESP32 to the Fanstel BC805M (nRF52805M) breakout board.

Problem: The Esp32 does not get a response from the BC805M.

Setup:

Hardware:

- The ESP32 is connected by usb cable to my Mac.

- The ESP32 connects the BC805M by four cables -> 3V3->VDD, GND->GND, Rx->Tx, Tx->Rx. Rx and Tx from ESP32 are Serial2 (not the Serial of the programmer).

Software:

- The BC805M still has the firmware from delivery. Fanstel points out, that this is "AT-ready" firmware. I can also connect via BLE to it (is this possible when the firmware is "AT-ready"?).

- The ESP32 is flashed by a simple Serial2 write/read arduino code:

#include <HardwareSerial.h>

#define RXD2 16
#define TXD2 17

 void setup() {
   Serial.begin(115200);
   Serial2.begin(115200, SERIAL_8N1, RXD2, TXD2);
   delay(1000);
   Serial.println("start");
 }
 void loop() {
   Serial2.write("AT\r\n");
  
   if(Serial2.available()){
     Serial.write(Serial2.read());  
   }
 }

- While monitoring this, the ESP32 receives no answer from BC805M. By this point I would expect to receive an "OK".

 

Additional Information:

• When I connect the two ESP32 Rx and Tx Serial2 Pins with each other the monitor prints AT AT AT ...  (so this works)
  
  
• When i connect the ESP32 with the BC805M not by crossing Tx and Rx but like: Rx->Rx, Tx->Tx; I receive the message BlueNor 200622 started! after I pressed the reset button on the BC805M
  
  
• The BC805M has a hardware-switch which I can change by hand and which is connected to P004. I am not completely sure about this, but I think this switch changes between "data mode" and "AT-command-mode":
  
  I am not sure if I have to connect the 3V3 also to the P004 to activate "AT-Mode". I already tried this and different switch positions, but nothing worked.
  
  
• The docs say: "The default baud rate is 115200, one stop bit and no parity". I guess I always respected that.
  
  
• connecting solely the BC805M per usb to my mac and running arduino IDE's monitor, the monitor prints absolutely nothing and writing AT-Commands also results in nothing. Weird.
  
  
• Could it be possible, that the BC805M is running the wrong firmware?

 

I appreciate any kind of help on this. All thoughts are welcome and please tell me if you need more information.
Thanks.

[run_ar]

Hi,

Unfortunately we are not familiar with the Fanstel module or their AT SW. Maybe you should try to contact Fanstel support?

[Fabchick]

Update 1: After messaging with Fanstel support I found out:

- The AT commands code is definitely preloaded on BC805M.

- The CMD/DATA mode is GPIO 04 (=P004). Setting it to high is command mode. I guess this is want I understand as "AT-Mode". So I connected a GPIO of the ESP to P004 and set it to high. Sadly, I am still getting no response from AT-Commands.

Could it be possible that the TX Pin of the BC805M is broken? How can I test it?

[Fabchick]

I am in contact with Fanstel, but maybe it is not a Fanstel-specific problem

[run_ar]

If I understand correctly you can receive data from the BCM805M? but you think there might be an issue with the TX? Maybe you could connect a logic analyzer to the uart interface to see what is happening i.e. do the host transfer any data to the BC805M?

[Fabchick]

The Fanstel support just wrote me that the BC805M Evaluation Board is NOT preloaded with the AT-Command firmware.

Only the BC805M module has it preloaded.

That explains why the AT-Commands did not work.