topic Re: OSC2 PIN AS GPIO OF MC908JL3ECDWE in 8-bit Microcontrollers

OSC2 PIN AS GPIO OF MC908JL3ECDWE

NaveenKumar — Tue, 01 Apr 2008 00:35:29 GMT

Hi

I am using Freescale chip MC908JL3ECDWE.As per my application need,I am using External RC oscillator.
Now OSC2 pin is available free and can be configured as a general purpose I/O pin PTA6 or as KBI(Keyboard Interrupt)

I have tried number of ways by doing manual coding, use of processor expert and beans on Code Warrior Compiler
in C language but couldn't get the result.

As per application need, it' has to be configured as INPUT pin but that particular pin is having floating voltage,approx
2.5V in all attempts.

Please help me out,I am very new to Freescale Micros.

Thanks

Re: OSC2 PIN AS GPIO OF MC908JL3ECDWE

bigmac — Wed, 02 Apr 2008 10:25:24 GMT

Hello, and welcome to the forum.

My understanding from the datasheet is that a different part number is required for the RC oscillator, than that with the crystal oscillator. This is an old device, and the part numbering system has now changed. Using the old part numbers, the standard part was MC68HC908JL3E, whereas the RC oscillator part was MC68HRC908JL3E. I am not sure whether the RC oscillator part is still available.

An alternative would be to select a device from the 9S08 family. These have an internal oscillator module, so don't consume any pins when this option is used. Perhaps select a device that has 8K of flash, and that is available in either 28-pin or 32-pin SM package. Maybe even select a 44-pin package and you will have plenty of I/O available.

Regards,

Mac

Re: OSC2 PIN AS GPIO OF MC908JL3ECDWE

bigmac — Wed, 02 Apr 2008 11:00:51 GMT

The following alternatives might be a possibility. For example, the MC9S08AW16 is likely to be about the same price as the 908JL3E, and the MC9S08AC16 will likely be even cheaper. These 44-pin devices should operate from the same voltage range as the current device.

Regards,

Mac

Re: OSC2 PIN AS GPIO OF MC908JL3ECDWE

peg — Wed, 02 Apr 2008 14:42:45 GMT

Hi,

bigmac wrote:

My understanding from the datasheet is that a different part number is required for the RC oscillator, than that with the crystal oscillator. This is an old device, and the part numbering system has now changed. Using the old part numbers, the standard part was MC68HC908JL3E, whereas the RC oscillator part was MC68HRC908JL3E. I am not sure whether the RC oscillator part is still available.

The above is certainly all true for the JK1 as I used the HRC and changed to the HC when they stopped the RC one. (with a crystal etc jammed in where the RC was) As they share the same datasheet I imagine this all hold true for the JL3.