Created
August 28, 2020 10:07
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/* | |
Compile and link | |
gcc -O6 -I/opt/vc/include -L/opt/vc/lib -lbcm_host -o nanoflash nanoflash.c | |
Run example (gpioDpin rising edge => o[ns] offset => d[ns] gpio18 pwm flash) | |
$ sudo killall pigpiod | |
$ sudo ./nanoflash o d | |
*/ | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <stdint.h> | |
#include <fcntl.h> | |
#include <time.h> | |
#include <sys/mman.h> | |
#include <sys/stat.h> | |
#include <sys/types.h> | |
#include <unistd.h> | |
#include <assert.h> | |
#define gpioDin 4 | |
#include <bcm_host.h> | |
#define PI_BASE_ADDR bcm_host_get_peripheral_address() | |
#define GPIO_BASE (PI_BASE_ADDR + 0x200000) | |
#define PWM_BASE (PI_BASE_ADDR + 0x20C000) | |
#define CLK_BASE (PI_BASE_ADDR + 0x101000) | |
#define CLK_LEN 0xA8 | |
#define GPIO_LEN 0xB4 | |
#define PWM_LEN 0x28 | |
#define PWM_CTL 0 | |
#define PWM_STA 1 | |
#define PWM_RNG1 4 | |
#define PWM_FIFO 6 | |
#define PWM_CTL_CLRF1 (1<<6) | |
#define PWM_CTL_USEF1 (1<<5) | |
#define PWM_CTL_MODE1 (1<<1) | |
#define PWM_CTL_PWEN1 (1<<0) | |
#define PWM_STA_EMPT1 (1<<1) | |
#define CLK_PASSWD (0x5A<<24) | |
#define CLK_CTL_MASH(x)((x)<<9) | |
#define CLK_CTL_BUSY (1 <<7) | |
#define CLK_CTL_KILL (1 <<5) | |
#define CLK_CTL_ENAB (1 <<4) | |
#define CLK_CTL_SRC(x) ((x)<<0) | |
#define CLK_CTL_SRC_PLLD 6 /* 500.0 MHz */ | |
#define CLK_DIV_DIVI(x) ((x)<<12) | |
#define CLK_DIV_DIVF(x) ((x)<< 0) | |
#define CLK_PWMCTL 40 | |
#define CLK_PWMDIV 41 | |
#define MAX_BITS 224 | |
typedef struct | |
{ | |
unsigned divider; | |
unsigned bits; | |
} pwm_clock_cfg_t; | |
unsigned base_nano[]={4, 8, 10, 20, 40, 80, 100, 200, 250, 500, 1000}; | |
static volatile uint32_t *clkReg = MAP_FAILED; | |
static volatile uint32_t *gpioReg = MAP_FAILED; | |
static volatile uint32_t *gpioReg2 = MAP_FAILED; | |
static volatile uint32_t *pwmReg = MAP_FAILED; | |
static void mynanosleep(unsigned nanos) | |
{ | |
struct timespec ts, tr; | |
ts.tv_sec = 0; | |
ts.tv_nsec = nanos; | |
while (nanosleep(&ts, &tr)) | |
{ | |
ts = tr; | |
} | |
} | |
int gpioSetMode(unsigned gpio, unsigned mode) | |
{ | |
int reg, shift; | |
reg = gpio/10; | |
shift = (gpio%10) * 3; | |
gpioReg[reg] = (gpioReg[reg] & ~(7<<shift)) | (mode<<shift); | |
return 0; | |
} | |
int gpioGetMode(unsigned gpio) | |
{ | |
int reg, shift; | |
reg = gpio/10; | |
shift = (gpio%10) * 3; | |
return (*(gpioReg + reg) >> shift) & 7; | |
} | |
static void initPWM(unsigned divider) | |
{ | |
/* reset PWM clock */ | |
clkReg[CLK_PWMCTL] = CLK_PASSWD | CLK_CTL_KILL; | |
mynanosleep(10000); | |
/* set PWM clock source as 500 MHz PLLD */ | |
clkReg[CLK_PWMCTL] = CLK_PASSWD | CLK_CTL_SRC(CLK_CTL_SRC_PLLD); | |
mynanosleep(10000); | |
/* set PWM clock divider */ | |
clkReg[CLK_PWMDIV] = CLK_PASSWD | CLK_DIV_DIVI(divider) | CLK_DIV_DIVF(0); | |
mynanosleep(10000); | |
/* enable PWM clock */ | |
clkReg[CLK_PWMCTL] = | |
CLK_PASSWD | CLK_CTL_ENAB | CLK_CTL_SRC(CLK_CTL_SRC_PLLD); | |
mynanosleep(100000); | |
/* reset PWM */ | |
pwmReg[PWM_CTL] = 0; | |
/* clear PWM status bits */ | |
pwmReg[PWM_STA] = -1; | |
mynanosleep(10000); | |
} | |
static void sendPulse(unsigned bits) | |
{ | |
int i; | |
uint32_t word; | |
if (bits == 0) bits = 1; | |
else if (bits > MAX_BITS) bits = MAX_BITS; | |
/* clear PWM fifo */ | |
pwmReg[PWM_CTL] = PWM_CTL_CLRF1; | |
mynanosleep(10000); | |
while (bits >= 32) | |
{ | |
pwmReg[PWM_FIFO] = -1; | |
bits -= 32; | |
} | |
if (bits) | |
{ | |
word = 0; | |
for (i=0; i<bits; i++) word |= (1<<(31-i)); | |
pwmReg[PWM_FIFO] = word; | |
} | |
pwmReg[PWM_FIFO] = 0; | |
/* enable PWM for serialised data from fifo */ | |
pwmReg[PWM_CTL] = PWM_CTL_USEF1 | PWM_CTL_MODE1 | PWM_CTL_PWEN1; | |
} | |
static uint32_t * mapMem(int fd, unsigned base, unsigned len) | |
{ | |
return mmap | |
( | |
0, | |
len, | |
PROT_READ|PROT_WRITE|PROT_EXEC, | |
MAP_SHARED|MAP_LOCKED, | |
fd, | |
base | |
); | |
} | |
pwm_clock_cfg_t getDivBits(unsigned nano) | |
{ | |
pwm_clock_cfg_t cfg; | |
unsigned i, base, bits, err, bestErr, bestBase, bestBits; | |
bestErr = -1; | |
for (i=0; i<sizeof(base_nano)/sizeof(unsigned);i++) | |
{ | |
bits = nano / base_nano[i]; | |
if (bits > MAX_BITS) bits = MAX_BITS; | |
err = nano - (bits * base_nano[i]); | |
if (err < bestErr) | |
{ | |
bestErr = err; | |
bestBase = base_nano[i]; | |
bestBits = bits; | |
} | |
} | |
cfg.divider = bestBase / 2; | |
cfg.bits = bestBits; | |
return cfg; | |
} | |
#define GPLEV0 13 | |
#define PI_BANK (gpio>>5) | |
#define PI_BIT (1<<(gpio&0x1F)) | |
#define PI_INPUT 0 | |
int gpioRead(unsigned gpio) | |
{ | |
if ((*(gpioReg + GPLEV0 + PI_BANK) & PI_BIT) != 0) return 1; | |
else return 0; | |
} | |
int main(int argc, char *argv[]) | |
{ | |
int fd, d, o; | |
pwm_clock_cfg_t cfg; | |
fd = open("/dev/mem", O_RDWR | O_SYNC); | |
if (fd<0) | |
{ | |
printf("need to run as root, e.g. sudo %s\n", argv[0]); | |
exit(1); | |
} | |
gpioReg = mapMem(fd, GPIO_BASE, GPIO_LEN); | |
gpioReg2 = gpioReg + GPLEV0; | |
pwmReg = mapMem(fd, PWM_BASE, PWM_LEN); | |
clkReg = mapMem(fd, CLK_BASE, CLK_LEN); | |
close(fd); | |
assert(argc == 1+2); | |
o = atoi(argv[1]); | |
assert((0 <= o) && (o <= 224000)); | |
d = atoi(argv[2]); | |
d = (d*3)/2; // Pi4B correction | |
assert((4 <= d) && (d <= 224000)); | |
cfg = getDivBits(d); | |
gpioSetMode(18, 2); /* set to ALT5, PWM1 */ | |
initPWM(cfg.divider); | |
gpioSetMode(gpioDin, PI_INPUT); | |
for(;;) | |
{ | |
while ((*gpioReg2 & 0x10) == 0) {} // 0x10: 1<<gpioDin | |
mynanosleep(o); | |
sendPulse(cfg.bits); | |
mynanosleep(d+1000); | |
while (gpioRead(gpioDin)) {} | |
} | |
} |
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