school project using led strip
Fork of PololuLedStrip by
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?
User | Revision | Line number | New 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 | } |