https://www.freetronics.com.au/pages/es ... 1Udm3lKi00
It is a carrier board for an ESP-01 that has a voltage regulator and level shifters. I need to say that the ESP is tested and works. The board is tested and works. I just cannot use pins 0 and 1 on an Uno or Mega (tried both Arduinos).
So it is important to note that I tried eliminating the jumpers on the board or bad solder joints by using wires to connect Tx/Tx and Rx/Rx. This is by connecting any of the row of 8 Rx pins to Rx to pin on the Mega and the same with TX. I am getting no transmit to the board. The light never blinks. If I reset, I get no garbage or firmware version, so no recieve. (I have tried an empty sketch on the Uno and Mega and tried pulling RST to ground).
But here is the part that makes no sense yet, If I take my jumper wires and move them on a mega to one of the other serial ports, like serial1, and upload an echo sketch where the USB serial talks to Serial1, it works perfectly. I type AT commands and see the responses. Of course in this setup it is Tx/Rx and Rx/Tx.
If I take the ESP-01 off the board, remove the board, and connect jumper wires to pins 0 and 1, it of course works. I suspected the level shifters, but by moving things to serial1 (or 2 or 3) on a Mega, it works. I'm lost.