Critical R4 WiFi defects and limitations to know before you waste your time

Official Hardware UNO Family UNO R4 WiFi
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I'm not knowledgeable on this subject, but I see this on the Renesas RA4M1 product page:

https://www.renesas.com/en/products/microcontrollers-microprocessors/ra-cortex-m-mcus/ra4m1-32-bit-microcontrollers-48mhz-arm-cortex-m4-and-lcd-controller-and-cap-touch-hmi#overview

  • 8kB Data Flash to store data as in EEPROM

and the EEPROM library bundled with the "Arduino UNO R4 Boards" platform does use flash:

Renesas provides specs for the data flash memory in table 48.72 of the "Renesas RA4M1 Group User’s Manual: Hardware" document:

https://www.renesas.com/en/products/microcontrollers-microprocessors/ra-cortex-m-mcus/ra4m1-32-bit-microcontrollers-48mhz-arm-cortex-m4-and-lcd-controller-and-cap-touch-hmi#documents

Table 48.72 Data flash characteristics (1)

Parameter Symbol Min Typ Max Unit Test conditions
Reprogramming/erasure cycle*1 NDPEC 100,000 1,000,000 - Times -
Data hold time after 10,000 times of NDPEC tDDRP 20*2, *3 - - Year Ta = +85°C
Data hold time after 100,000 times of NDPEC tDDRP 5*2, *3 - - Year Ta = +85°C
Data hold time after 1,000,000 times of NDPEC tDDRP - 1*2, *3 - Year Ta = +25°C
  • Note 1. The reprogram/erase cycle is the number of erasure for each block. When the reprogram/erase cycle is n times (n = 100,000),
    erasing can be performed n times for each block. For instance, when 1-byte programming is performed 1,000 times for different
    addresses in 1-byte blocks, and then the entire block is erased, the reprogram/erase cycle is counted as one. However,
    programming the same address for several times as one erasure is not enabled. Overwriting is prohibited.
  • Note 2. Characteristics when using the flash memory programmer and the self-programming library provided by Renesas Electronics.
  • Note 3. These results are obtained from reliability testing.