ESP32 Forum

I'm using esp32 dev module to send hex byte to MCP39F511 power ic. This ic can response over uart if received valid hex byte, example if i send "0xA5 0x04 0x53 0xFC" from esp32 to these ic then ic will response hex byte=0x06(Acknowledge). But i am having difficulty how to send data as hex byte and how to get response from power ic. I used the source code of espidf but still only sending ascii and not hex bytes. I'm using espidf. Thank you and hope every help me please!

To represent bytes, or any numerical value, in C, you need to write them as numbers, not as strings.
e.g.
defines an array of 4 bytes with the values you provided. In fact, there is no such thing as a "hex byte"; but in C code you can write numeric literals, e.g. byte values, in different bases: 0xA5 is exactly the same as 165 or 0b10100101‬.
While 0xA5 in C code is a number, "0xA5" (notice the quotation marks!) is a 4-character string.
For text output/logging the value is converted into readable ASCII; the single byte value 0xA5 would be converted into the 3 characters '1', '6', and '5'.