nodeMCU download/init failing
Posted: Mon Mar 20, 2017 7:11 pmI've got a circuit that hooks a nodeMCU to the remote control for an audio recorder. In normal use, this R/C talks to the recorder with a 2400 baud serial line, running at 3.3V. That makes it nice and easy to power the R/C from the nodeMCU board.
Another nodeMCU is connected to the recorder itself, and so the pair together basically constitute a wireless remote. Everything from the R/C side gets broadcast as a UDP packet on port 2390; everything coming back is broadcast as a UDP packet on port 2385. And at each end, the messages are sent out to the relevant device using a software serial on pins 7 and 8 configured to 2400 baud.
This whole setup actually works OK, at least when I have both nodeMCUs connect to my wireless modem. I'm still not able to make it work with the R/C side configured as an access point and the recorder side configured as a station, but I think that's just some stupid typo.
I'm developing using the Arduino application on a mac.
But there's a problem: if I try to download a new program to the nodeMCU while the R/C is plugged into it, I get a communication failure. It just won't manage to make the download happen. (The connection to the R/C is 4 wires: Gnd, 3.3V, Tx, Rx, and the R/C clearly has some little processor inside it.) In the same way, when I do download a program (with the RC unplugged) and then plug it in, but want to restart it, I press the reset button on the nodeMCU ... and nothing happens.
I wondered if there might be a problem with some signal from the R/C interfering somehow ... or something else about these things that I just don't understand.
The wiring is dead simple: USB from the mac to microUSB on the nodeMCU; wires from GND, 3.3V, D7, and D8, going to the GND, +, Tx, and Rx pins on the nodeMCU (where I might have Rx and Tx swapped -- I'm describing this from memory). Should I have some capacitors in there somewhere? Does pin D7 or D8 have a special meaning during startup that I'm not aware of?
I'd appreciate any thoughts/suggestions that folks might have. If there's further info you need, please let me know.
Another nodeMCU is connected to the recorder itself, and so the pair together basically constitute a wireless remote. Everything from the R/C side gets broadcast as a UDP packet on port 2390; everything coming back is broadcast as a UDP packet on port 2385. And at each end, the messages are sent out to the relevant device using a software serial on pins 7 and 8 configured to 2400 baud.
This whole setup actually works OK, at least when I have both nodeMCUs connect to my wireless modem. I'm still not able to make it work with the R/C side configured as an access point and the recorder side configured as a station, but I think that's just some stupid typo.
I'm developing using the Arduino application on a mac.
But there's a problem: if I try to download a new program to the nodeMCU while the R/C is plugged into it, I get a communication failure. It just won't manage to make the download happen. (The connection to the R/C is 4 wires: Gnd, 3.3V, Tx, Rx, and the R/C clearly has some little processor inside it.) In the same way, when I do download a program (with the RC unplugged) and then plug it in, but want to restart it, I press the reset button on the nodeMCU ... and nothing happens.
I wondered if there might be a problem with some signal from the R/C interfering somehow ... or something else about these things that I just don't understand.
The wiring is dead simple: USB from the mac to microUSB on the nodeMCU; wires from GND, 3.3V, D7, and D8, going to the GND, +, Tx, and Rx pins on the nodeMCU (where I might have Rx and Tx swapped -- I'm describing this from memory). Should I have some capacitors in there somewhere? Does pin D7 or D8 have a special meaning during startup that I'm not aware of?
I'd appreciate any thoughts/suggestions that folks might have. If there's further info you need, please let me know.