David Knight / PololuLedStrip

This library lets you control the addressable RGB LED strips from Pololu Robotics. Forked to add selectable colour order (Support RGB or GRB Leds)

Fork of PololuLedStrip by David Grayson

PololuLedStrip.cpp@12:b6df8ac053c8, 2013-03-01 (annotated)

Committer:
DavidEGrayson
Date:
Fri Mar 01 04:34:54 2013 +0000
Revision:
12:b6df8ac053c8
Parent:
10:f1bb84b97788
Child:
13:9c72841ec45e
Introduced the delay_fudges array.  The code still works for the M0.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
DavidEGrayson 1:102307d9b701 1 #include "PololuLedStrip.h"
DavidEGrayson 1:102307d9b701 2
DavidEGrayson 1:102307d9b701 3 bool PololuLedStrip::interruptFriendly = false;
DavidEGrayson 1:102307d9b701 4
DavidEGrayson 7:9a088f042ee0 5 uint8_t led_strip_write_delays[3];
DavidEGrayson 4:d3b60bd43811 6
DavidEGrayson 12:b6df8ac053c8 7 static const uint8_t delay_fudges[] = { 32, 0, 0 };
DavidEGrayson 12:b6df8ac053c8 8
DavidEGrayson 7:9a088f042ee0 9 void PololuLedStrip::calculateDelays()
DavidEGrayson 7:9a088f042ee0 10 {
DavidEGrayson 8:1578776ceac5 11 // Get the clock frequency in MHz.
DavidEGrayson 8:1578776ceac5 12 int f_mhz = SystemCoreClock / 1000000;
DavidEGrayson 8:1578776ceac5 13
DavidEGrayson 8:1578776ceac5 14 // Arrange for a 700 nanosecond delay between the rise time and the fall time for a 0 bit.
DavidEGrayson 10:f1bb84b97788 15 led_strip_write_delays[0] = 700*f_mhz/1000 - 32;
DavidEGrayson 8:1578776ceac5 16
DavidEGrayson 8:1578776ceac5 17 // Arrange for a 600 nanosecond delay between the fall time for a 0 bit and the fall time for a 1 bit.
DavidEGrayson 8:1578776ceac5 18 // This means the pulses representing a 1 will be 700+600 = 1300 nanoseconds.
DavidEGrayson 12:b6df8ac053c8 19 led_strip_write_delays[1] = 600*f_mhz/1000;
DavidEGrayson 8:1578776ceac5 20
DavidEGrayson 8:1578776ceac5 21 // Arrange for a 1200 nanosecond delay between the fall time for a 1 bit and rise time of the next bit.
DavidEGrayson 8:1578776ceac5 22 // This means the period of the signal will be 2500 nanoseconds.
DavidEGrayson 12:b6df8ac053c8 23 led_strip_write_delays[2] = 1200*f_mhz/1000;
DavidEGrayson 10:f1bb84b97788 24
DavidEGrayson 12:b6df8ac053c8 25 for(int i = 0; i < 3; i++)
DavidEGrayson 12:b6df8ac053c8 26 {
DavidEGrayson 12:b6df8ac053c8 27 if (led_strip_write_delays[i] < delay_fudges[i])
DavidEGrayson 12:b6df8ac053c8 28 {
DavidEGrayson 12:b6df8ac053c8 29 led_strip_write_delays[i] = 0;
DavidEGrayson 12:b6df8ac053c8 30 }
DavidEGrayson 12:b6df8ac053c8 31 else
DavidEGrayson 12:b6df8ac053c8 32 {
DavidEGrayson 12:b6df8ac053c8 33 led_strip_write_delays[i] -= delay_fudges[i];
DavidEGrayson 12:b6df8ac053c8 34 led_strip_write_delays[i] <<= 1;
DavidEGrayson 12:b6df8ac053c8 35 }
DavidEGrayson 12:b6df8ac053c8 36 }
DavidEGrayson 7:9a088f042ee0 37 }
DavidEGrayson 6:9d0530b7dae2 38
DavidEGrayson 1:102307d9b701 39 PololuLedStrip::PololuLedStrip(PinName pinName)
DavidEGrayson 1:102307d9b701 40 {
DavidEGrayson 1:102307d9b701 41 gpio_init(&gpio, pinName, PIN_OUTPUT);
DavidEGrayson 1:102307d9b701 42 }
DavidEGrayson 1:102307d9b701 43
DavidEGrayson 1:102307d9b701 44 void PololuLedStrip::write(rgb_color * colors, unsigned int count)
DavidEGrayson 1:102307d9b701 45 {
DavidEGrayson 8:1578776ceac5 46 calculateDelays();
DavidEGrayson 8:1578776ceac5 47
DavidEGrayson 1:102307d9b701 48 __disable_irq(); // Disable interrupts temporarily because we don't want our pulse timing to be messed up.
DavidEGrayson 7:9a088f042ee0 49
DavidEGrayson 1:102307d9b701 50 while(count--)
DavidEGrayson 1:102307d9b701 51 {
DavidEGrayson 9:6ffb85d69eaf 52 led_strip_write_color(colors, gpio.reg_set, gpio.reg_clr, gpio.mask);
DavidEGrayson 9:6ffb85d69eaf 53 colors++;
DavidEGrayson 9:6ffb85d69eaf 54
DavidEGrayson 1:102307d9b701 55 if (interruptFriendly)
DavidEGrayson 1:102307d9b701 56 {
DavidEGrayson 1:102307d9b701 57 __enable_irq();
DavidEGrayson 1:102307d9b701 58 __nop();
DavidEGrayson 1:102307d9b701 59 __nop();
DavidEGrayson 1:102307d9b701 60 __nop();
DavidEGrayson 1:102307d9b701 61 __disable_irq();
DavidEGrayson 1:102307d9b701 62 }
DavidEGrayson 1:102307d9b701 63 }
DavidEGrayson 1:102307d9b701 64
DavidEGrayson 1:102307d9b701 65 __enable_irq(); // Re-enable interrupts now that we are done.
DavidEGrayson 1:102307d9b701 66 wait_us(24); // Hold the line low for 24 microseconds to send the reset signal.
DavidEGrayson 9:6ffb85d69eaf 67
DavidEGrayson 9:6ffb85d69eaf 68 //*(gpio.reg_set) = gpio.mask;
DavidEGrayson 9:6ffb85d69eaf 69 //*(gpio.reg_clr) = gpio.mask;
DavidEGrayson 9:6ffb85d69eaf 70
DavidEGrayson 1:102307d9b701 71 }