[Venus638FLPx-L] getting NACK for every command I send

Hello SparkFun Colleagues!

I am to-be-happy owner of [Venus638FLPx-L.

Facts:

  • Using Raspberry pi, Tx from RPI connected to Rx of GPS and vice versa.

  • Module powered up with 3.3V

  • EMEIA data is coming fine from Venus (for example with command: cat /dev/ttyAMA0)

I would like to change baud rate, update rate etc. So I am trying to send the commands to the devices, however, regardless what I send, I am getting 0x84 (NACK) information.

Simplest possible example (from Linux terminal, similar story when I send commands from C), asking the device to move into binary mode:

echo -e "\xA0\xA1\x00\x03\x09\x02\x00\x0B\x0D\x0A" > /dev/ttyAMA0

Answer I am getting (the answer is somewhere between EMEIA data):

A0 A1 02 84 09 8D 0A 0A

(please note that the answer doesn’t come in […] 0x0D, 0x0A format…)

I am getting similar answers when trying other commands, like getting device info (0x02).

Question is:

What I am doing wrong that Venus doesn’t want to reply with ACK and execute the command?

Greetings,

Koza](https://www.sparkfun.com/products/11058)