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PIC16F877 code on a PIC16F77

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2005-2006 » Archive through 07 December, 2005 » PIC16F877 code on a PIC16F77 « Previous Next »

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Darren
Frequent Contributor
Username: Darren

Post Number: 76
Registered: 05-2005

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Posted on Monday, 05 December, 2005 - 09:51 pm:   Edit Post Delete Post Print Post

Hi all,
I was just wondering if anyone has had a similar experience to the following. I built a circuit initially using a PIC16F77 and all worked fine - using the on board ADC's and SPI module. Some time later I thought as the 'F77 is getting a bit old now I'd use a 'F877 instead to make it easier for anyone wanting to build my circuit to get the PIC required. I discovered today that I accidently programmed a 'F77 with the source code for the 'F877 and it still works perfectly, even though the 'list' and 'include' files aren't correct and the 'F877 has a 10 bit ADC instead of 8 bit - the result registers are different 'F77 = ADRES and 'F877 = ADRESl and ADRESH.
Anyone had/found a similar experience?
Regards,
Darren
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Microguy
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Username: Microguy

Post Number: 591
Registered: 09-2005

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Posted on Monday, 05 December, 2005 - 10:35 pm:   Edit Post Delete Post Print Post

I haven't looked, but it wouldn't suprise me that they would make it "backwards compatible".

Like the ADC registers, you were using 8 bits, now they're split, into two registers. But guess what? The lower register of the new chip, has the same number of bits and address of the old chip. Meaning if you want to access the other two bits, you need to read another register. Or you're still just using the lower 8 out of 10 bits.

(I don't know which)

But then again, maybe you just got lucky too, from what I've seen with MicroChip!

(and again, I don't know which!)


Sort of like upgrading from a 8086 processor to a NEC V30.

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