ESP-Now UIFlow to Arduino

[Xio1996]

Dear All,

I am trying to send a message using the EspNow blocks in UIFlow to an ESP32 running an Arduino program. The message is sent and received but I can't seem to get the data in the Arduino program it just returns '1' even though the length alters as I alter the data being sent. When I look at the Python code it is sending a string, so I think I'm asking how to convert a Python string into an Arduino string/character array. Sorry if this is a real newbie question.

Blocky - Python code
def buttonA_wasPressed():
global iCount
espnow.send(id=1, data=str('HELLO!'))
pass
btnA.wasPressed(buttonA_wasPressed)

Arduino ESP-Now receive code
void OnDataRecv(const uint8_t *mac_addr, const uint8_t *data, int data_len)
{
char macStr[18];
char sData[data_len];

snprintf(macStr, sizeof(macStr), "%02x:%02x:%02x:%02x:%02x:%02x",
mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
Serial.print("Last Packet Recv from: "); Serial.println(macStr);
Serial.print("Data Length: "); Serial.println(data_len);
Serial.print("Last Packet Recv Data: "); Serial.println(*data);
Serial.println("");
}

Arduino Output
11:39:37.342 -> Last Packet Recv from: d8:a0:1d:55:4b:38
11:39:37.342 -> Data Length: 16
11:39:37.342 -> Last Packet Recv Data: 1
11:39:37.342 ->

[lukas]

Hey

since you pass a pointer to the println-function and the cpu does not know what type of data is located at that position this behaviours seems normal.
In the example in the link they create a structure for the transmitted data. In the callback they copy the recieved data in this structure and later you can print exactly what you want:
https://randomnerdtutorials.com/esp-now-esp32-arduino-ide/

[Xio1996]

Hi Lukas,

Thank you for the link. I will see if I can use their method. I did find a solution that works.

I noticed that the received data starting at index 11 was getting ASCII codes so I modified the Arduino code to construct a String starting from that position. The ESP-Now OnDataRecv callback now looks like this (the string construction is in bold).

void OnDataRecv(const uint8_t *mac_addr, const uint8_t *data, int data_len)
{
char macStr[18];

String tData="";
char Ascii[1];
for(int i=10;i<data_len;i++)
{
tData+=(char)data[i];
}

snprintf(macStr, sizeof(macStr), "%02x:%02x:%02x:%02x:%02x:%02x",
mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);

Serial.print("Last Packet Recv from: "); Serial.println(macStr);
Serial.print("Data Length: "); Serial.println(data_len);
Serial.print("Last Packet Recv Data: '"); Serial.print(tData);
Serial.println("'");
}

Arduino Output

13:38:11.806 -> Last Packet Recv from: d8:a0:1d:55:4b:38
13:38:11.806 -> Data Length: 22
13:38:11.806 -> Last Packet Recv Data: 'Hello World!'

[fbritop]

@xio1996 I was trying to do the same thing. I have some ESP01 relay controlers, which they work fine between them aand an ESP32 WROOM. I'm now trying to use a Core2 as a master, but I haven't been able to communicate with the ESP01.

Do you have any example codes for Core5 in MicroPython?

Thanks in advance
FBP