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kmsywulakmsywula
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Green pixel fix
JIRA: ATLEDGE-470
1 parent a6381cb commit 0a38234

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+73
-123
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1 file changed

+73
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‎libraries/Adafruit_NeoPixel/Adafruit_NeoPixel.cpp

+73-123
Original file line numberDiff line numberDiff line change
@@ -1021,143 +1021,93 @@ void Adafruit_NeoPixel::show(void) {
10211021

10221022
// Arduino 101 -----------------------------------------------------------
10231023

1024-
PinDescription *pindesc = &g_APinDescription[pin];
1025-
uint8_t *p = pixels, *end = p + numBytes;
1026-
register uint8_t pix, mask;
1024+
#define NOPx7{ __builtin_arc_nop(); \
1025+
__builtin_arc_nop(); __builtin_arc_nop(); \
1026+
__builtin_arc_nop(); __builtin_arc_nop(); \
1027+
__builtin_arc_nop(); __builtin_arc_nop(); }
10271028

1029+
PinDescription *pindesc = &g_APinDescription[pin];
1030+
register uint32_t loop = 8 * numBytes; // one loop to handle all bytes and all bits
1031+
register uint8_t *p = pixels;
1032+
register uint32_t currByte = (uint32_t) (*p);
1033+
register uint32_t currBit = 0x80 & currByte;
1034+
register uint32_t bitCounter = 0;
1035+
register uint32_t first = 1;
1036+
1037+
// The loop is unusual. Very first iteration puts all the way LOW to the wire -
1038+
// constant LOW does not affect NEOPIXEL, so there is no visible effect displayed.
1039+
// During that very first iteration CPU caches instructions in the loop.
1040+
// Because of the caching process, "CPU slows down". NEOPIXEL pulse is very time sensitive
1041+
// that's why we let the CPU cache first and we start regular pulse from 2nd iteration
10281042
if (pindesc->ulGPIOType == SS_GPIO) {
10291043
register uint32_t reg = pindesc->ulGPIOBase + SS_GPIO_SWPORTA_DR;
1030-
register uint32_t reg_val = __builtin_arc_lr((volatile uint32_t)reg);
1044+
uint32_t reg_val = __builtin_arc_lr((volatile uint32_t)reg);
10311045
register uint32_t reg_bit_high = reg_val | (1 << pindesc->ulGPIOId);
10321046
register uint32_t reg_bit_low = reg_val & ~(1 << pindesc->ulGPIOId);
10331047

1034-
while(p < end) {
1035-
pix = *p++;
1036-
for(mask = 0x80; mask; mask >>= 1) {
1037-
__builtin_arc_sr(reg_bit_high, (volatile uint32_t)reg);
1038-
if(pix & mask) {
1039-
__builtin_arc_nop();
1040-
__builtin_arc_nop();
1041-
__builtin_arc_nop();
1042-
__builtin_arc_nop();
1043-
__builtin_arc_nop();
1044-
__builtin_arc_nop();
1045-
__builtin_arc_nop();
1046-
__builtin_arc_nop();
1047-
__builtin_arc_nop();
1048-
__builtin_arc_nop();
1049-
__builtin_arc_nop();
1050-
__builtin_arc_nop();
1051-
__builtin_arc_nop();
1052-
__builtin_arc_nop();
1053-
__builtin_arc_nop();
1054-
__builtin_arc_nop();
1055-
__builtin_arc_sr(reg_bit_low, (volatile uint32_t)reg);
1056-
__builtin_arc_nop();
1057-
__builtin_arc_nop();
1058-
__builtin_arc_nop();
1059-
__builtin_arc_nop();
1060-
__builtin_arc_nop();
1061-
__builtin_arc_nop();
1062-
__builtin_arc_nop();
1063-
__builtin_arc_nop();
1064-
} else {
1065-
__builtin_arc_nop();
1066-
__builtin_arc_nop();
1067-
__builtin_arc_nop();
1068-
__builtin_arc_nop();
1069-
__builtin_arc_nop();
1070-
__builtin_arc_nop();
1071-
__builtin_arc_nop();
1072-
__builtin_arc_nop();
1073-
__builtin_arc_nop();
1074-
__builtin_arc_nop();
1075-
__builtin_arc_sr(reg_bit_low, (volatile uint32_t)reg);
1076-
__builtin_arc_nop();
1077-
__builtin_arc_nop();
1078-
__builtin_arc_nop();
1079-
__builtin_arc_nop();
1080-
__builtin_arc_nop();
1081-
__builtin_arc_nop();
1082-
__builtin_arc_nop();
1083-
__builtin_arc_nop();
1084-
__builtin_arc_nop();
1085-
__builtin_arc_nop();
1086-
__builtin_arc_nop();
1087-
__builtin_arc_nop();
1088-
__builtin_arc_nop();
1089-
__builtin_arc_nop();
1090-
__builtin_arc_nop();
1091-
__builtin_arc_nop();
1092-
}
1048+
loop += 1; // include first, special iteration
1049+
while(loop--) {
1050+
if(!first) {
1051+
currByte <<= 1;
1052+
bitCounter++;
1053+
}
1054+
1055+
// 1 is >550ns high and >450ns low; 0 is 200..500ns high and >450ns low
1056+
__builtin_arc_sr(first ? reg_bit_low : reg_bit_high, (volatile uint32_t)reg);
1057+
if(currBit) { // ~400ns HIGH (740ns overall)
1058+
NOPx7
1059+
NOPx7
1060+
}
1061+
// ~340ns HIGH
1062+
NOPx7
1063+
__builtin_arc_nop();
1064+
1065+
// 820ns LOW; per spec, max allowed low here is 5000ns */
1066+
__builtin_arc_sr(reg_bit_low, (volatile uint32_t)reg);
1067+
NOPx7
1068+
NOPx7
1069+
1070+
if(bitCounter >= 8) {
1071+
bitCounter = 0;
1072+
currByte = (uint32_t) (*++p);
10931073
}
1074+
1075+
currBit = 0x80 & currByte;
1076+
first = 0;
10941077
}
10951078
} else if(pindesc->ulGPIOType == SOC_GPIO) {
10961079
register uint32_t reg = pindesc->ulGPIOBase + SOC_GPIO_SWPORTA_DR;
1097-
register uint32_t reg_val = MMIO_REG_VAL(reg);
1080+
uint32_t reg_val = MMIO_REG_VAL(reg);
10981081
register uint32_t reg_bit_high = reg_val | (1 << pindesc->ulGPIOId);
10991082
register uint32_t reg_bit_low = reg_val & ~(1 << pindesc->ulGPIOId);
11001083

1101-
while(p < end) {
1102-
pix = *p++;
1103-
for(mask = 0x80; mask; mask >>= 1) {
1104-
MMIO_REG_VAL(reg) = reg_bit_high;
1105-
if(pix & mask) {
1106-
__builtin_arc_nop();
1107-
__builtin_arc_nop();
1108-
__builtin_arc_nop();
1109-
__builtin_arc_nop();
1110-
__builtin_arc_nop();
1111-
__builtin_arc_nop();
1112-
__builtin_arc_nop();
1113-
__builtin_arc_nop();
1114-
__builtin_arc_nop();
1115-
__builtin_arc_nop();
1116-
__builtin_arc_nop();
1117-
__builtin_arc_nop();
1118-
__builtin_arc_nop();
1119-
__builtin_arc_nop();
1120-
__builtin_arc_nop();
1121-
__builtin_arc_nop();
1122-
MMIO_REG_VAL(reg) = reg_bit_low;
1123-
__builtin_arc_nop();
1124-
__builtin_arc_nop();
1125-
__builtin_arc_nop();
1126-
__builtin_arc_nop();
1127-
__builtin_arc_nop();
1128-
__builtin_arc_nop();
1129-
__builtin_arc_nop();
1130-
__builtin_arc_nop();
1131-
} else {
1132-
__builtin_arc_nop();
1133-
__builtin_arc_nop();
1134-
__builtin_arc_nop();
1135-
__builtin_arc_nop();
1136-
__builtin_arc_nop();
1137-
__builtin_arc_nop();
1138-
__builtin_arc_nop();
1139-
__builtin_arc_nop();
1140-
__builtin_arc_nop();
1141-
__builtin_arc_nop();
1142-
MMIO_REG_VAL(reg) = reg_bit_low;
1143-
__builtin_arc_nop();
1144-
__builtin_arc_nop();
1145-
__builtin_arc_nop();
1146-
__builtin_arc_nop();
1147-
__builtin_arc_nop();
1148-
__builtin_arc_nop();
1149-
__builtin_arc_nop();
1150-
__builtin_arc_nop();
1151-
__builtin_arc_nop();
1152-
__builtin_arc_nop();
1153-
__builtin_arc_nop();
1154-
__builtin_arc_nop();
1155-
__builtin_arc_nop();
1156-
__builtin_arc_nop();
1157-
__builtin_arc_nop();
1158-
__builtin_arc_nop();
1159-
}
1084+
loop += 1; // include first, special iteration
1085+
while(loop--) {
1086+
if(!first) {
1087+
currByte <<= 1;
1088+
bitCounter++;
11601089
}
1090+
MMIO_REG_VAL(reg) = first ? reg_bit_low : reg_bit_high;
1091+
if(currBit) { // ~430ns HIGH (740ns overall)
1092+
NOPx7
1093+
NOPx7
1094+
__builtin_arc_nop();
1095+
}
1096+
// ~310ns HIGH
1097+
NOPx7
1098+
1099+
// 850ns LOW; per spec, max allowed low here is 5000ns */
1100+
MMIO_REG_VAL(reg) = reg_bit_low;
1101+
NOPx7
1102+
NOPx7
1103+
1104+
if(bitCounter >= 8) {
1105+
bitCounter = 0;
1106+
currByte = (uint32_t) (*++p);
1107+
}
1108+
1109+
currBit = 0x80 & currByte;
1110+
first = 0;
11611111
}
11621112
}
11631113

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