Assign an array to an ESB Payload ?

Question

Hi, 
 Currently tinkering with ESB comms, everything is fine but I was wondering whether there is a simple way to assign an array to a payload. For now, I have 2 int variables, say 301 and 257 and I assign each digits to the payload: tx_payload.data[0] = 3; tx_payload.data[1] = 0; tx_payload.data[2] = 1; tx_payload.data[3] = 2; tx_payload.data[4] = 5; tx_payload.data[5] = 7; 
 and do the same on the RX side, decomposing them into numbers. In order to assign those two int variables into the payload, I tried to achieve this into a char string (of 6) like "301257" and then assign this to tx_payload.data without success. Is there any way to assign 2 int variables directly into the payload and the other way around, something like value1 = rx_payload.data[0..2] and value2 = rx_payload.data[3..5] ? Any help or hint GREATLY appreciated 
 Steve

Mike Thompson · Answer

Hi Steve, the payload data is itself an array of unsigned 8-bit values (uint8_t). There are many ways to do what you describe, but one way would be to dereference the array elements as pointers to 32-bit values and assign them directly. It might look something as follows (putty the values into variables is optional). uint32_t num1 = 301; uint32_t num2 = 257; *((uint32_t *) &tx_payload.data[0]) = num1; *((uint32_t *) &tx_payload.data[4]) = num2; tx_payload.length = sizeof(uint32_t) * 2; Then on the receiving side, do the opposite dereference the values from the received payload data. uint32_t num1, num2; num1 = *((uint32_t *) &rx_payload.data[0]); num2 = *((uint32_t *) &rx_payload.data[4]); You will probably want to familiarize yourself with how C handles pointers into arrays and type conversion. It's quite a bit different than other languages that you may be more familiar with. Mike

Assign an array to an ESB Payload ?

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