Hi, Friends!

I'm using a copter with Speedybee F405 v3 FC board stack.

I'd like to use some of the FC controller pins as PINIO pins but have certain problems. For example when I use LED_STRIP pin Is working properly but if I use SERIAL#6 TX/RX pins there are problems that I cannot explain -- lack of power or signal interruption or anything else. When I use LED#1 and LED_STRIP then the signal on the LED#1 is changes synchronously to the LED_STRIP pin:



Can anybody give any recommendation which MCU pins are the best as PINIO and how the FC board pins are mapped to MCU pins? Is there any document that lists MCU/board pin mapping?

I would be glad to hear the expert opinions.

Thanks!

If you FC has onboard programmable LEDs then it will likely be connected to the same pin as the LED pin, in which case you do not want to use it for PINIO. If your board has a SerialTX/RX pin that is a good choice, otherwise pretty much any MCU pin should work, I have used RX/TX and BUZ- pins on various boards. What do you have connected that does not seem to work with the serial pins?

You might be on a hiding to nothing with that particular FC. The SpeedyBee F405 V3 FC is riddled with a number of design flaws that give all sorts of hardware conflicts. To name but a couple, you can't use DSHOT and RPM filtering without turning on DSHOT bitbang (which you shouldn't have to do on an F4 FC) due to dma/timer conflicts, and you can't switch on both analog OSD and blackbox logging at the same time due to an SPI conflict, so you have to choose one or the other. I think they must have tasked a trainee with the design of that FC without it then being peer reviewed by an experienced designer.

You seem to know what you are doing with configuring PINIO, but the fact that you can't seem to get it working and have issues that in your own words you "cannot explain", it suggests that there are also some conflicts with other hardware IO communications on the board as well, so it's going to be trial and error, and even then you might not be able to get it working. Members on here can make some suggestions but with the known flaws in that FC it will just be guesswork, the same as you would have to do.

You might be better off just cutting your losses and replacing the FC with one that doesn't have so many known issues. Ironically SpeedyBee have just released a V4 of the same FC which supposedly fixes all the design issues that has plagued the V3.