PNP Controller Firmware and Example PCB

This firmware was projected to control a PNP machine through G/M-codes. The microcontroller used is the MSP430G2553, found in the LaunchPad G2 development boards. This build was tested with MSP430-GCC 6_1_1_0 based on GCC 7.3.2.154 from Texas Instruments website.

This PNP has six stepper motors:

• two on the Y axis, one connected with reverse phases;
• one on the X axis;
• one on the Z axis;
• one on the C axis (Z axis rotation);
• one on the solder extruder.

Only the Y axis motors share the same DIR and STEP inputs.

The vacuum valve is also controlled by the MCU (Microcontroller Unit) using an phototransistor optocoupler.

Firmware build instructions

1. Install MSPDebug and slac640y https://dlbeer.co.nz/articles/slac460y/index.html
2. Install MSP430-GCC from Texas Instruments website http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSPGCC/latest/index_FDS.html
3. Configure the compiler and libraries location in the Makefile
4. Run a make recipe
5. Program MSP with mspdebug.

Makefile recipes

Update the CC and CPPFLAGS to match the your development environment. The Makefile was configured to generate a program optimised for size and will emit warnings for common mistakes.

• make devredo will clear the screen, execute make clean and compile and link the source files and libraries. A map file will be generated after the linking process.
• make devclean will execute make clean and clear the screen.
• make clean will clear the outputs (*.o and *.elf).
• make will compile and link if necessary.

Microcontroller pinout

The microcontroller pinout is:

Pin no.	Port no.	Function
1			DVCC (3,3 V)
2	P1.0		SWX (X negative endstop INPUT with PULL-UP)
3	P1.2		UCA0RXD
4	P1.3		UCA0TXD
5	P1.4		SWY (Y negative endstop INPUT with PULL-UP)
6	P1.5		DIR_Y (Y axis stepper motors direction OUTPUT)
7	P1.6		DIR_X (X axis stepper motor direction OUTPUT)
8	P2.0		STEP_Y (Y axis stepper motors step OUTPUT)
9	P2.1		STEP_X (X axis stepper motor step OUTPUT)
10	P2.2		DIR_Z (Z axis stepper motor step OUTPUT)

Pin no.		Port no.	Function
20				DVSS (GND)
19		P2.6		SWZ (Z negative endstop INPUT with PULL-UP)
18		P2.7		VACUUM (vacuum valve OUTPUT)
17				TEST
16				RST
15		P1.7		STEP_S (solder extruder stepper motor OUTPUT)
14		P1.6		STEP_RZ (C axis stepper motor OUTPUT)
13		P2.5		STEP_Z (Z axis stepper motor OUTPUT)
12		P2.4		DIR_S (solder extruder direction OUTPUT)
11		P2.3		DIR_RZ (C axis stepper motor OUTPUT)

Supported G/M-codes

All the G/M-codes supported use only absolute coordinates in millimetres with a precision of six decimal places. Exponential notation is not supported.

The feedrate is defined internally and is not modifiable via any code.

The command will be executed if the sent string reaches 64 characters or if an ASCII null byte (\0), *, (, or ; is sent.

The machine will issue the string "done" after each command is performed correctly.

Supported G-codes

• G0 Xnnnnn.nnnnnn Ynnnnn.nnnnnn Znnnnn.nnnnnn Cnnnnn.nnnnnn Ennnnn.nnnnnn or G1 Xnnnnn.nnnnnn Ynnnnn.nnnnnn Znnnnn.nnnnnn Cnnnnn.nnnnnn Ennnnn.nnnnnn will move the motors in a linear fashion. If the machine is in an error status (error flag is set), it will refuse to move unless an automatic or manual calibration is performed. The user does not need to send all the positions at once.
  The movement is performed first in the X, Y and Z axis using Bresenham's line algorithm. After these axis have reached their desires position, the C axis is moved, performing a Z axis rotation and, at last, the extruder motor is moved to the specified position.
  If any endstop is triggered during X, Y, and Z axis movement, the machine will halt and must be reset.

• G33 will start the auto calibration routine. If the routine is successful the machine will clear the error flag and set an auto calibration flag. The error flag will be set if any unexpected condition is detected in the routine.
  The calibration routine will move X, Y and Z axis to their origins in this order.

• G92 Xnnnnn.nnnnnn Ynnnnn.nnnnnn Znnnnn.nnnnnn Cnnnnn.nnnnnn Ennnnn.nnnnnn will set the current position. Useful for manual calibration. The error flag is always cleared if this command is executed, so it must be used with caution. The positions do not need to be sent at once.

Supported M-codes

• M10 will turn the vacuum on.

• M11 will turn the vacuum off.

• M114 will print the system position (X, Y, Z axis and solder extruder), auto calibration flag, error flag and vacuum valve status.