Extra digital outputs?

[DDanielMK]

Good day Firstly, this is a very cool project. Thanks for putting in all of the effort and making it freely available @fra589.

I am using Mega5X to control a 5-axis 3D printing apparatus for my research project. I have 13 outputs that I need to be able to turn on/off individually. Previously when I was operating the machine in 3-axis mode with Marlin, I used 13 of the Ramps pins that are meant for the screen as digital outputs, and used M42 to toggle between 0 and 5V.

I have now got the four available digital output pins working with Mega5X using M62/63. Is it at all possible to add extra digital outputs? As far as I can see there are still unused pins on the Ramps board, alongside the digital IO pins that have already been allocated.

This would avoid me having to connect up a second Arduino to the Ramps and use the existing four outputs from the Ramps to tell the second Arduino what to do, which will be a bit of a complicated and roundabout way of doing it.

I would appreciate any suggestions.

Thanks!

[fra589]

Hi @DDanielMK,

It should be not too difficult to do... The output pins are defined in cpu_map.h, from line 224 to 237. You can add your needed pins here. Each pin is defined with it's DDR, PORT ans BIT. See the Arduino doc (https://docs.arduino.cc/retired/hacking/hardware/PinMapping2560/) and the cpu_map.h mapping definition in the wiki (https://github.com/fra589/grbl-Mega-5X/wiki/Pinout-mapping-in-cpu_map.h) to define your own supplementary pins.

Then, in digital_control.c:

• change the type of function: uint8_t digital_get_state() to uint16_t digital_get_state()
• and the variable at line 56: uint8_t digital_state = DIGITAL_OUTPUT_STATE_OFF;to uint16_t digital_state = DIGITAL_OUTPUT_STATE_OFF;
• Add the lines to drive your new output pins:
• in the function digital_init() after the line 30,
• in the function digital_get_state() after the line 85 (7 lines to add for each new pins, copy and increment the already defined pins)
• change the function void digital_stop(const uint8_t mode) to void digital_stop(const uint16_t mode)
• and add your new pins after line 153,
• change the function void digital_set_state(uint8_t mode) to void digital_set_state(uint16_t mode),
• and add your new pins after the line 214
• change the function void digital_sync(uint8_t mode) to void digital_sync(uint16_t mode)

In the gcode.c (line 30) file, change the max number of your digital output to #define MAX_DIGITAL_OUTPUT 13 (the maximum you will can put here will be 16), Then, from line 1557 to line 1573, change all the uint8_t types to uint16_t.

This should be work...

Please, report if it work for you.

@++; Gauthier.

[DDanielMK]

Thank you @fra589 for the detailed instructions. Those steps worked, except I also had to define the extra outputs in ditigal_control.h, and change all instances of uint8_t to uint16_t in the same file.

I am using digital pins 16, 17, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43 and 45. I don't need to use 27 to 33 as inputs, so I re-defined them as outputs instead.

The only thing that is puzzling me now is how to invert the digital output pins so I don't have to re-wire my relays. I have defined INVERT_DIGITAL_OUTPUT_PIN_X for all the output pins in config.h. I have also added the necessary code for each pin in the _void digitalstop and _void digital_setstate functions in digital_control.c. Only the first four pins are inverted and the rest stay like they were. Is there a setting that I am missing somewhere?

Thanks for the help :)

[fra589]

Hello @DDanielMK,

Those steps worked, except I also had to define the extra outputs in ditigal_control.h, and change all instances of uint8_t to uint16_t in the same file.

Sure ! Sorry, I forget this as it was obvious for me :-)

The only thing that is puzzling me now is how to invert the digital output pins so I don't have to re-wire my relays. I have defined INVERT_DIGITAL_OUTPUT_PIN_X for all the output pins in config.h. I have also added the necessary code for each pin in the _void digitalstop and _void digital_setstate functions in digital_control.c. Only the first four pins are inverted and the rest stay like they were. Is there a setting that I am missing somewhere?

It should work. Please, post your config.h and digital_control.c & .h files, so I wil can verify it...

By the way, you also need to modify the report.c file to add the report of all your added outputs. The report of currently digital defines output is made from line 836 to 839.

@++; Gauthier.

[DDanielMK]

Thanks @fra589

I have attached the files.

Mega5x.zip

[fra589]

I don't see anything wrong, except that you have 14 outputs and not 13. :smile:

Can you also send your cpu_map.h and gcode.c so I will can make complete test on my development board?

@++; Gauthier.

[DDanielMK]

Here are the other two files. I'll change the number of outputs, thanks.

CPUmap and Gcode.zip

[fra589]

Hi @DDanielMK ,

I found the bug! :smile: In fact, your extra pins were working in reverse as you want, but it was their initialization that wasn't working.

In the function digital_init() in the file digital_control.c, there is a small line (number 41) which call digital_stop(0x0F); And the mode 0x0F specify only the first 4 bits! => So the first 4 outputs. Change the ilne 42 to: digital_stop(0xFFFF); And grbl-Mega-5X will work as you want.

@++; Gauthier. P.S. I send to you the modified file report.c where I added the report for all your digital outputs. report.c.zip

[DDanielMK]

Thank you @fra589 :-)