ESP8266 ESP-01S Relay Module Relay WIFI Smart Socket with ESP-01S
I powered on - and nothing happened. The red power light on the ESP-01S came on as usual, but there is none of the familiar blue flash on startup.
A little check with a multi-meter revealed that GPIO0 and CH_PD were not at the high (ie 3.3V) voltage level required for startup. A quick search on the Internet unearthed a schematic which confirmed this:
|The relay module schematic has no provision for GIO0 and CH_PD tied high|
The modification is easy enough - I tied GPIO0 high (ie to 3.3V) using a 10K resistor as the schematic showed it was also used to control the relay. CH_PD I tied directly to 3.3V, but you are encouraged to use a 10K resistor as well.
|Modifications to GPIO0 and CH_PD|
And that was all it took- it powered on quite happily (I used a modified version of the Arduino IDE Blink sketch.
|Working ESP-01S relay module|