Short question before I solder speaker to my radio module: the datasheet
speaks of a programming of the module via TTL (38400).
Now I had tried it out, with 3 options:
a.) the photon with wires directly to the radio (TX<>RX, RX<>TX, GND+3V3) and the code snippet here:
//int inByte = Serial1.read();
b.) with a USB2Serial module and
c.) with a YP-05 FDDI module and send AT commands via Arduino IDE/Serial Monitor
Am I on the right track, because I failed with all options?
For example, via AT-Command to set a new station frequency.
I didn’t read anything about that module emulating a serial modem and so using AT command doesn’t make sense. nevermind… farther down all the commands start with AT.
TTL stands for Transitor-Transistor-Logic… Or simply, it uses 0-5V signaling. Since the Particle devices only output 3.3V max, you need a logic-level shifter between the Particle device and the radio module (and that also implies needing a 5V supply).
The radio module can be operated between 3 and 5.5V. Even if I switch from the Photon 3V3 to V from the radio, it starts. Do you think that a logical level shifter is necessary? I have one in the office with 2x 4 PINs here (vcc, scl, sda, gnd) - Can I take that to shift only the voltage (I tested this without success
Perhaps not. But since you were having issues, it was logical to interpret TTL as requiring 5V signals. 3.3v signaling is referred to as CMOS logic if I remember correctly.
Thanks so far, I have to organize an LLS.