jepler/wifi-ntp-pps
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

add an offset to get better agreement with gps pps

Browse source
This commit is contained in:
Jeff Epler 2022-01-08 14:29:52 -06:00
parent d671c3c9b0
commit 78aca62e89
No known key found for this signature in database
GPG key ID: D5BF15AB975AB4DE
1 changed files with 16 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

17
main/wifi_ntp_pps.c
View file

@ -37,6 +37,10 @@ void time_sync_notification_cb(struct timeval *tv)
gettimeofday(&last_set, NULL);
}
// Measure the delay from GPS PPS to this thing's PPS. A
// *POSITIVE* offset means that this thing is LATE.
#define PPS_OFFSET_MS 14
#define US_IN_S (1000000)
#define RED 1,0,0
#define GREEN 0,1,0
#define CYAN 0,1,1
@ -104,7 +108,18 @@ void app_main(void)
while(true) {
struct timeval tv;
gettimeofday(&tv, NULL);
const unsigned duty = 100000;
// apply the OFFSET
tv.tv_usec += PPS_OFFSET_MS * 1000;
if(tv.tv_usec < 0) {
tv.tv_sec -= 1;
tv.tv_usec += US_IN_S;
} else if(tv.tv_usec > US_IN_S) {
tv.tv_sec += 1;
tv.tv_usec -= US_IN_S;
}
const unsigned duty = US_IN_S/10;
bool state = tv.tv_usec < duty;
gpio_set_level(GPIO_PPS, state);