This is my attempt at porting Remora (https://github.com/scottalford75/Remora)
a free, opensource LinuxCNC component and Programmable Realtime Unit (PRU)
to stm32f4 (STM32F407vg to be exact that's what I have).
 
Modules Implemented so far:
	Blinker
	Reset
	Stepgen
	Switch	- not tested
	Estop		- not tested
	DigitalPin	- not tested	
	
Configuration is sent via serial port @115200 8N1

Enumeration for the type of function
 ESTOP 			 = 0,
 STEPGEN, 	 = 1
 DIGITAL_PIN = 2 
 RESET_PIN   = 3
 RC_SERVO		 = 4
 TEMPERATURE = 5
 ENCODER		 = 6
 SWITCH			 = 7
 BLINKER		 = 8
 
Data Format:

Stepgen data format "#B13,C0C1C2,C3C4C5,C6C7C8"
	B13 B=BaseThread 1=Type1 3=Number of joints<-MUST HAVE exactly the same number of joints to cofigure
	C0 PortC StepPin 0
	C1  PortC DirPin 1
	C2 PortC EnablePin 2
	...

Blinker data format "#S8,E0F4"
	S8 = ServoThread Type8
	E0 = PortE Pin 0
	F4 = Frequency of the blink, 	only value is used
	
Reset Pin data format "#S3,C15;"
	S3 ServoThread Type3
	C15 PortC Pin15

eStop Pin data format "#S0,C12"
	S0 ServoThread Type 0
	C12 PortC Pin12


Switch data format "#S7,E0F4"
	S7 = ServoThread Type8
	E0 = PortE Pin 0
	M1 = Mode 0=off 1=on 	only value is used
	V0 = PV index 				only value is used
	S25.5 = SP 						only value used


Digital Pin data format "#S2,A6M1B0I0P0U1Z0"
	S2 = ServoThread Type 2
	A6 = PortA Pin 6
	M1 = Mode 1=input 0=output, 					only value is used
	B0 = Data bit, 												only value is used
	I0 = Invert 1=inverted 0=normal, 			only value is used
	P0 = Output type 0=PUSH_PULL 1=OPEN_DRAIN, 			only value is used
	U1 = PullUp/Down 0=none 1=pull-up 2=pull-down, 	only value is used
	Z2 = Speed 0=low 1=medium 2=fast 3=high, 				only value is used 

SerialPort on Port A9:A10
 TX: A9
 RX: A10

SPI1 on Port A4:A7
 SPI1_NSS:  PA4
 SPI1_SCK:  PA5
 SPI1_MiSO: PA6
 SPI1_MOSI: PA7

At power up or reset, system will hang arround at "2. Load Configuration"
it will wait for special character '$' the data must be sent along with it
stringed together or per function followed by carriage return (ENTER on serial terminal) (0x0D)

e.g.
--Configure 3 joints on Port C0:C8, blinker on Port E0, reset on Port C15, eStop on Port C12
$#B13,C0C1C2,C3C4C5,C6C7C8#S8,E0F4#S3,C15#S0,C12

--Configure 3 joints on Port C0:C8, blinker on Port E0, reset on Port C15
$#B13,C0C1C2,C3C4C5,C6C7C8#S8,E0F4#S3,C15

--Configure just one function, blinker at PortE pin 0
$#S8,E0F4

--Configure more blinker at once, 
$#S8,E0F4#S8,C0F2,#S8,C6F10



There is no error checking (yet) done on the data,
the data format has to be followed. The data string is up to 128 characters
including the special characters as long as it's a complete format
The plan is to use a gui to send configuration
(I'm hoping data can be made sure to be correct before sending)
All parameters with "only value is used", any character can be used as long as it's A to Z
   
I have tested it with Rpi4 2GB LinuxCNC 2.8.2, STM32F407vg with
Remora-XYZ config with AXIS gui and the splash nc file

First time pressing the eStop button will say it's running
then suddenly will reset and go idle (I'm not sure yet why).
The second time pressing the eStop button should stay in Running state.
Then the splash nc file can be run.

Hope to get more skilled coder improve my very obvious amateur work and make it stable for all.


Library used is https://github.com/andysworkshop/stm32plus with a few mods.
Unfortunately the library supported a limited series of STM32F4 microcontrollers
due to an older stdperipheral library used.

***This is an Eclipse project with GCC-Arm plugins (not STM32CUBE),
hopefully I can learn enough make or scons or cmake
to make this easy to build without IDE or somebody do it ;-)

keep having fun, and don't forget to share :-)
(c) 2021 mhel marcelo [email protected]