I own a few of the HM-TRP uart radio modules and have successfully programmed one for higher speed. I noticed that when I disconnected the power to the module and then powered it about 5 minutes later that my settings are still intact. My power supply is 3.3V through an LM1117-3.3 regulator with 10uF connected to input and 100uF capacitors connected to output. I don't think their values are high enough to cause data retention. and the only other capacitor I used in the entire circuit is 47nF.
This suggests to me that these modules have special kind of ROM that allows long-term storage, but the question is how long would such storage last for before the settings are automatically reset to defaults?
This suggests to me that these modules have special kind of ROM that allows long-term storage, but the question is how long would such storage last for before the settings are automatically reset to defaults?