It seems that during the start up phase it seems that pin 21 gets set high, which causes one of my relays to always be on.. This pin is allocated to a servo related to the camera. If i remove the allocation in HW it still goes high during boot. If i boot the pi by itself it stays idle. Any ideas where to start looking..
wow thanks for the prompt answer, I did a reinstall and now it works exactly as you say. The relay hat board I had laying around uses pin 21 to drive one of the relays, so nothing I can do with that except for wiring it directly. Thanks this has saved me so much effort and I have been having fun as well- Great project that works well so far.
The raspberry has some pins that during the startup-phase gets High or Low.
This is due to whatever happen during startup and I suppose it cannot be controlled.
For this reason in my SW setting I've chosen the PINs to control the relays which do not have this issue during startup and assigned other PIN like the GPIO21 to other functions.
If you remove the GPIO21 from the hardware list this is going to be ignored from the SW.
Not quite sure what you mean by "if you boot the PI by yourself" it stays idle. When I boot the PI with Raspbian, the GPIO21 will always go LOW (with raspberry pi3).
If you set the GPIO21 to work with a relay, then after the start-up phase the SW will get control of the PIN and set it high or low according to the setting.
Normally the relays works in negative logic, so the pin low will mean Relay activated. For this reason there is a field in the Hardware table which is called "logic" can be set "neg or "pos" according to the relay types.