topic Re: EEprom writes unreliably - 9S08PT32 in 8-bit Microcontrollers

EEprom writes unreliably - 9S08PT32

larrymitschke — Sat, 26 Apr 2014 13:24:32 GMT

Hi,

I am getting some bytes that do not write correctly in eeprom (some left blank at FF and some 00) when setting default values on first powerup. I suspected the eeprom clock running too fast, but the FCLKDIV register is set per the data sheet:

Crystal 4Mhz

Bus Clk 2Mhz

NVM_FCLKDIV = 0X01 // for fclk of 1Mhz

Because it acts as if the clk is too fast, I set the FCLKDIV to 0X02 to slow it down. Now it programs the eeprom all correctly, but I don't see this as a solution because I am worried about overstressing the eeprom over time. Am I missing something that I have overlooked?

I am using the Cosmic compiler and their library routines, and they have verified that the routines work correctly on their test setup.

Re: EEprom writes unreliably - 9S08PT32

pgo — Sat, 26 Apr 2014 13:59:18 GMT

Hi Larry,

An obvious question is how are you setting up the Processor Clock. Are you sure it's operating with a bus frequency of 2MHz (FBE/FBELP with a BDIV of 1)?

bye

Re: EEprom writes unreliably - 9S08PT32

larrymitschke — Sat, 26 Apr 2014 14:26:24 GMT

Absolutely. I even ran the bus clk out to a pin to double check, and it is at 2Mhz.

Thanks.

Re: EEprom writes unreliably - 9S08PT32

larrymitschke — Fri, 25 Jul 2014 13:50:39 GMT

Problem turned out to be the WDT timing out in the middle of saving default values in the first-time-power-up routine. Upon restart, the software thought all the default settings were filled and bypassed the EEprom routine, leaving blank addresses.