LED Strip with K64F
Fork of PololuLedStrip by
Embed:
(wiki syntax)
Show/hide line numbers
PololuLedStrip.cpp
00001 #include "PololuLedStrip.h" 00002 00003 bool PololuLedStrip::interruptFriendly = false; 00004 00005 // The two timed delays, in units of half-cycles. 00006 uint8_t led_strip_write_delays[2]; 00007 00008 void PololuLedStrip::calculateDelays() 00009 { 00010 int f_mhz = SystemCoreClock / 1000000; // Clock frequency in MHz. 00011 00012 if (f_mhz <= 48) 00013 { 00014 // The delays below result in 360/1120 ns pulses and a 1880 ns period on the mbed NXP LPC11U24. 00015 led_strip_write_delays[0] = 0; 00016 led_strip_write_delays[1] = 0; 00017 } 00018 else 00019 { 00020 // Try to generally compute what the delays should be for a ide range of clock frequencies. 00021 00022 // The fudge factors below were experimentally chosen so that we would have 00023 // ~100/840 ns pulses and a ~1430 ns period on the mbed NXP LPC1768 (96 MHz Cortex-M3). 00024 // There seem to be some ~100 ns inconsistencies in the timing depending on which example program is 00025 // running; the most likely explanation is some kind of flash caching that affects the timing. 00026 // If you ever change these numbers, it is important to check the the subtractions below 00027 // will not overflow in the worst case (smallest possible f_mhz). 00028 led_strip_write_delays[0] = 750*f_mhz/1000 - 33; 00029 led_strip_write_delays[1] = 550*f_mhz/1000 - 20; 00030 } 00031 00032 // Convert from units of cycles to units of half-cycles; it makes the assembly faster. 00033 for(int i = 0; i < 2; i++) 00034 { 00035 led_strip_write_delays[i] <<= 1; 00036 } 00037 } 00038 00039 PololuLedStrip::PololuLedStrip(PinName pinName) 00040 { 00041 gpio_init_out(&gpio, pinName); 00042 } 00043 00044 void PololuLedStrip::write(rgb_color * colors, unsigned int count) 00045 { 00046 calculateDelays(); 00047 00048 __disable_irq(); // Disable interrupts temporarily because we don't want our pulse timing to be messed up. 00049 00050 while(count--) 00051 { 00052 led_strip_write_color(colors, gpio.reg_set, gpio.reg_clr, gpio.mask); 00053 colors++; 00054 00055 if (interruptFriendly) 00056 { 00057 __enable_irq(); 00058 __nop(); 00059 __nop(); 00060 __nop(); 00061 __disable_irq(); 00062 } 00063 } 00064 00065 __enable_irq(); // Re-enable interrupts now that we are done. 00066 wait_us(24); // Hold the line low for 24 microseconds to send the reset signal. 00067 00068 //*(gpio.reg_set) = gpio.mask; 00069 //*(gpio.reg_clr) = gpio.mask; 00070 00071 }
Generated on Fri Jul 15 2022 20:00:56 by 1.7.2