libPBX

A Raspberry Pi driver library for the Pixelblaze 8-64 channel expander, based on Ben Hencke's PBDriverAdapter library for Arduino.

It depends on wiringPi. A note for users of newer Raspberry Pis: the original creator/maintainer of wiringPi dropped the project, so if you need to get the updated version for 4b, try http://wiringpi.com/wiringpi-updated-to-2-52-for-the-raspberry-pi-4b/ or https://github.com/WiringPi/WiringPi (which seems to still be somewhat active?).

Currently supports WS2812 family LEDs.

Usage example: 'bounce'

#include <wiringPi.h> /* for delay() */
#include <math.h>
#include <errno.h>

#include "pbx.h"

#define NUMPIXELS 10

int main ()
{
    lx_pbx_init (1);
    lx_pbx_driver_t pbx;
    lx_pbx_driver_create ("/dev/ttyS0", &pbx)
    lx_pbx_ws2812_chan_t chan;
    lx_pbx_open_channel_ws2812 (
        /* channel number= */0,
        &chan,
        LX_PBX_CHANNEL_RGB,
        /* Send the green component first, followed by red and then blue; the white
        component is ignored */
        1, 0, 2, 0);
    int bounce_pos  = 0;
    int bounce_step = 1;
    while (1) {
        uint8_t data[NUMPIXELS][3];
        uint8_t r, g, b;
        for (int i = 0; i < NUMPIXELS; i++) {
            if (bounce_pos == i) {
                data[i][0] = 0x85;
                data[i][1] = 0x24;
                data[i][2] = 0x21;
            } else {
                data[i][0] = 0x48;
                data[i][1] = 0x16;
                data[i][2] = 0x84;
            }
        }
        bounce_pos += bounce_step;
        if (bounce_pos == NUMPIXELS) bounce_step = -1, bounce_pos = NUMPIXELS - 2;
        if (bounce_pos == -1) bounce_step = +1, bounce_pos = 1;

        lx_pbx_driver_write_ws2812_chan (&pbx, &chan, (uint8_t *)&data, NUMPIXELS);
        lx_pbx_driver_draw_accumulated (&pbx);

        delay (10);
    }

    lx_pbx_driver_destroy (&pbx);
    return 0;
}

Building

git clone https://github.com/bosporos/libpbx.git
cd libpbx
clang -c -o libpbx.so pbx.c

API

int lx_pbx_init(int needs_wpi_setup)

Should be called once at the beginning of the program.

If needs_wpi_setup is nonzero, then it lx_pbx_init will call wiringPiSetup(). If you are separately initializing wiringPi (e.g. calling one of the wiringPiSetupXXX() functions), then make sure to pass 0 so that wiringPi does not get initialized twice.

Returns 0 on success.

int lx_pbx_driver_create(const char * device_file, lx_pbx_driver_t * driver)

Initialize a new driver attached to a given serial port. device_file should be the path to the appropriate serial port (e.g. /dev/ttyS0, etc.).

Example:

lx_pbx_driver_t my_driver;
lx_pbx_driver_create("/dev/serial0", &my_driver);

Returns 0 on success, LX_PBX_NO_DRIVER if an error occurs. In the event of an error, the error will be in errno.

int lx_pbx_driver_write_ws2812_chan(const lx_pbx_driver_t * driver, lx_pbx_ws2812_chan_t channel, uint8_t * pixel_data, size_t pixel_num)

Buffer pixel_data to a given channel according to the settings in channel. To actually draw the buffered pixel data, use lx_pbx_driver_draw_accumulated(lx_pbx_driver_t * driver).

pixel_data should be a contiguous block of memory containing the data of pixel_num pixels, formatted according to channel->channel_type. LX_PBX_CHANNEL_RGB specifies that each set of three bytes will be one byte of red, one byte of blue, one byte of green, in that order.

By setting pixel_data to NULL, pixel_num to 0, and channel->channel_type to LX_PBX_CHANNEL_DISABLED, then channel may be disabled.

Returns 0 on success, otherwise will return the error. Possible errors: EINVAL, ENXIO.

int lx_pbx_driver_draw_accumulated(lx_pbx_driver_t * driver)

Draws buffered channel from all channels.

Returns 0 on success, otherwise will return the value of the error. Possible errors: EINVAL, ENXIO.

int lx_pbx_driver_destroy(lx_pbx_driver_t * driver)

Teardown function, closes the serial port that driver has open.

Will return 0 on success, otherwise the value of the error. Possible errors: EINVAL, ENXIO.

int lx_pbx_open_channel_ws2812 (uint8_t chan_no, lx_pbx_ws2812_chan_t * channel, uint8_t chan_type, uint8_t red_i, uint8_t green_i, uint8_t blue_i, uint8_t white_i)

Initializes channel, binding it to channel number chan_no and changing its type to chan_type. red_i, green_i, blue_i, and white_i are used to specify the order in which color components are sent to the LEDs. (You may need to tinker around with this to get the colors to come out properly)

Returns 0 on success, otherwise the value of the error. Will return EINVAL if channel is invalid, ENOTSUP if chan_type is not recognized, EDOM if any of red_i, etc. are greater than 3.

int lx_pbx_set_channel_comp_ws2812 (lx_pbx_ws2812_chan_t * channel, uint8_t chan_type)

Changes the channel type of channel to chan_type.

Returns 0 on success, otherwise the value of the error. Will return EINVAL if channel is invalid, and ENOTSUP if chan_type is not recognized.

Troubleshooting

• It may be necessary to fiddle around with the color component ordering in lx_pbx_open_channel_ws2812. (For the strip of ws2812b's I was testing with, I ended up with 1,0,2 for red, green, blue, but I'm not sure if that'll work for everyone).

• On Raspberry Pi (I use Ubuntu Server as my OS), I had to disable the default-enabled serial console by removing console=/dev/<serial port>,115200 from /boot/cmdline.txt.

• You may need a logic level converter between your Pi and the Pixelblaze Expander.