rtcmem module documentation

###rtcmem module

• rtcmem.read32()
• rtcmem.write32()

#rtcmem module The RTC in the ESP8266 contains memory registers which survive a deep sleep, making them highly useful for keeping state across sleep cycles. Some of this memory is reserved for system use, but 128 slots (each 32bit wide) are available for application use. This module provides read and write access to these.

Due to the very limited amount of memory available, there is no mechanism for arbitrating use of particular slots. It is up to the end user to be aware of which memory is used for what, and avoid conflicts. Note that some Lua modules lay claim to certain slots.

####See also

• [rtctime module]
• [rtcfifo module]

rtcmem.read32(idx [,num])

####Description Reads num 32bit values from the RTC user memory, starting at index idx (zero-based). If num is not specified, a value of 1 is assumed.

If idx is outside the valid range [0,127] this function returns nothing. If num results in overstepping the end of available memory, the function only returns the data from the valid slots.

####Example

val = rtcmem.read32(0) -- Read the value in slot 0
val1, val2 = rtcmem.read32(42, 2) -- Read the values in slots 42 and 43

rtcmem.write32(idx, val [, val2, ...] )

####Description Writes one or more values to RTC user memory, starting at index idx.

Writing to indices outside the valid range [0,127] has no effect.

####Example

rtcmem.read32(0, 53) -- Store the value 53 in slot 0
rtcmem.read32(42, 2, 5, 7) -- Store the values 2, 5 and 7 into slots 42, 43 and 44, respectively.