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Tips and questions relating to the GPS modules from SFE
By koza
Hello SparkFun Colleagues!

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

- 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:
Code: Select all
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):
Code: Select all
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?