ESP8266-01 and RF 433 modules

Hi everyone!

I’m building a device that can transmit and receive data by 433MHz radio modules/ managed by ESP-01.

RF modules are cheap FS1000A transmitter and XY-MK-5V receiver.

The should be able either to transmit or receive data at the moment not both. So I added a switch that supplies power to only one RF module at a time. And DATA pin of both modules are connected to the GPIO2.

The device scheme is attached.

Basically it works.

But I have an issue on start up the device. If the switch S2 is in the position of supplying power to the transmitter, then device is not starting correctly when attach the battery. The blue led is constantly light on the ESP and it is not send any data. In this case the ESP start correctly only of to disconnect GPIO2 when power on the battery.
When the S2 is supplying power to receiver on start up all goes right.

I would appreciate any advices on fixing this issue.

Thanks.

I’m sorry I don’t know how to edit posted message, so I will put the update here:

The switch I mentioned is not S2, but S1.

May not be part of your problem, but from the circuit it seems the 433 Mhz receiver is running off 9 V, which as they are designed only for 5 V wont do it much good, and as its a super regen , its likely to be off frequency, as the quench oscillator drifts with supply voltage.

mauried: May not be part of your problem, but from the circuit it seems the 433 Mhz receiver is running off 9 V, which as they are designed only for 5 V wont do it much good, and as its a super regen , its likely to be off frequency, as the quench oscillator drifts with supply voltage.

Yes, this is a second issue I would like to get advice. I choose 9V battery because it will give more distance for transmitter. But I need a way to get 5V for receiver. How is it possible without adding another DC step down module?

Try another GPIO or possibly a stronger pull up on GPIO2. I fought a very similar on my ESP-12. I’m powering the 433Mhz transmiter with 3.3v. About 50% of the time, I would get a solid blue led at boot up. Strangely the problem started when I added an antenna to the 433Mhz transmitter module. GPIO2 must be high for the esp8266 to boot and while the esp8266 has an internal pull-up, I suspect that the 433Mhz transmitter is pulling the pin low.