ESP8266 Community Forum

- Fri Jun 05, 2015 12:18 pm #19577 Actually, this is more an electronics problem than that to do with lua.

I have a project running on the ESP8266 01, with both gpios being used as outputs.

My code works fine, *but* at switch on, both pins pulse high for about 300ms, before the code takes over and switches them off. This is completely unacceptable, as one of the gpios operates a solenoid to open a door, and wouldnt want that to happen every time there is a power on!

I have determined that no amount of changes to the code would help; wrote a simple script that just configures the pins as outputs, and keeps them low, just as a test. Even then, the pins do flash high for a few milliseconds.

Can anyone suggest a hardware solution to suppress this, short of using a 555 monoshot?

Regards.

- Fri Jun 05, 2015 1:00 pm #19581

Actually, this is more an electronics problem than that to do with lua.

I have a project running on the ESP8266 01, with both gpios being used as outputs.

My code works fine, *but* at switch on, both pins pulse high for about 300ms, before the code takes over and switches them off. This is completely unacceptable, as one of the gpios operates a solenoid to open a door, and wouldnt want that to happen every time there is a power on!

I have determined that no amount of changes to the code would help; wrote a simple script that just configures the pins as outputs, and keeps them low, just as a test. Even then, the pins do flash high for a few milliseconds.

Can anyone suggest a hardware solution to suppress this, short of using a 555 monoshot?

Regards.

I would prefer the old fashion way:
Schmitt triggers inverter + change your "HI" and "LOW" commands, 1 -> LOW, 0 -> HIGH

ESP8266 MPDMv4 AC MAINS Dimmer Home: http://esp8266-projects.com/2016/04/mpdmv4-mains-dimmerswitch-html/
Available on Tindie: https://www.tindie.com/products/nEXT_EVO1/universal-ac-mains-dimmer-mpdmv41/

- Sat Jun 06, 2015 5:22 am #19632 Hi
Two possible things to try are to use either a pull down resistor( perhaps 10k or less) or use an RC circuit on the output.

Gerry

- Fri Jun 12, 2015 2:22 am #20235 Surprisingly, the pull-down didnt help.

Eventually just programmed a pic 12F629 as a dedicated initial 1 second delay line. The ESP drives the pic, the pic controls the relay. I know its an overkill, but served the purpose very well. A single component solution, with perhaps the world's shortest pic program sunning!