Enable MAX limit switches for F446

[px0001]

Hi, I'm developing an STM32F446 controller board with 16 digital inputs + 16 digital outputs + RS485 VFD control, so plenty of I/O available. Is it possible to enable MAX limit inputs (X/Y/Z) in the F4xx driver?

Regards,
Peter

[terjeio]

It is possible bu requires a bit of code changes in driver.c.
Be aware that limit and control inputs need to be on unique pin numbers (regardless of ports) due to how GPIO interrupts are handled.

[px0001]

How do I go about this, is there code in some other driver I could copy/translate?

The idea of my project is to use standard 24V industrial proximity sensors in NC configuration as end limit switches with a dedicated digital input per sensor.

The layout is:
Digital inputs = PA0-PA8, PA11-PA13, PB12-PB15
Digital outputs = PC0-PC5, PB0-PB9
So in this case PA12/13 and PB12/13 would collide if both used for limits or control inputs, but could be used for aux input?
I could probably remap the design and dedicate the whole of PA0-PA15 for digital inputs if I use USART3 on PC10/11 for host communication instead.

I checked the driver.c file and could see a single reference to X/Y/Z_LIMIT_PIN_MAX:

#ifdef X_LIMIT_PIN_MAX
signals.max.x = DIGITAL_IN(X_LIMIT_PORT_MAX, X_LIMIT_PIN_MAX);
#endif
#ifdef Y_LIMIT_PIN_MAX
signals.max.y = DIGITAL_IN(Y_LIMIT_PORT_MAX, Y_LIMIT_PIN_MAX);
#endif
#ifdef Z_LIMIT_PIN_MAX
signals.max.z = DIGITAL_IN(Z_LIMIT_PORT_MAX, Z_LIMIT_PIN_MAX);
#endif

Regards,
Peter

[terjeio]

The F7 driver has the needed code, but be aware that the DIGITAL_IN macros refers to the pin xx_BIT_MAX, not xx_PIN_MAX definition required by the F4 driver.

[px0001]

Great, I'll have a look at that. Anything else I should think of/be aware of? The purpose is for the board to be 100% compatible with grblhal and LinuxCNC/Remora SPI for medium sized machines, ie where you would use 24V I/O and external drivers housed in an automation cabinet.

Regards,
Peter