Deep sleep maximum time 8266

maxgerhardt · August 5, 2020, 7:29am

So this function is defined as

esp8266/Arduino/blob/9afb084159096aefa509aa2a9f962d15c7f5f146/cores/esp8266/Esp.h#L96


      
          class EspClass {
              public:
                  // TODO: figure out how to set WDT timeout
                  void wdtEnable(uint32_t timeout_ms = 0);
                  // note: setting the timeout value is not implemented at the moment
                  void wdtEnable(WDTO_t timeout_ms = WDTO_0MS);
          
                  void wdtDisable();
                  void wdtFeed();
          
                  void deepSleep(uint64_t time_us, RFMode mode = RF_DEFAULT);
                  void deepSleepInstant(uint64_t time_us, RFMode mode = RF_DEFAULT);
                  uint64_t deepSleepMax();
          
                  bool rtcUserMemoryRead(uint32_t offset, uint32_t *data, size_t size);
                  bool rtcUserMemoryWrite(uint32_t offset, uint32_t *data, size_t size);
          
                  void reset();
                  void restart();
          
                  uint16_t getVcc();

And thus uint64_t means the range of this value is between 0 and (2^64)-1 equals

18446744073709551615

your expression evaluates to

2220000000

which is below the max value; however you are doing int aka int32_t arithmetic when you don’t suffix the values with stuff like U, UL or ULL. And int32_t has a range of

−2147483648 (most negative)
2147483647 (most positive)

2220000000 (your number)

so as you can see you are above the int32_t limit; No need to worry though, just do unsigned long long arithmetic (for uint64_t) and write

 #define SleepTime (35ULL* 60ULL* 1000000ULL)

and you should be good to go.

Too-long-didn’t-read-version: You made a int32_t overflow, use ULLto calculate sleep time as the correct uint64_t value.