Hello,
I made a board with a dsPIC30F5011 20I/PTG 043540G (the chip is revision mg3 a1, probably an engineering sample, I have some tens of them I'd like to use for prototypes).
All worked ok until I made it execute this code sequence (I wanted to see if LP 32.768KHz clock could be slowed down):

                mov.b   #0x00,w0                ; value to put into OSCCONH
                mov     #OSCCONH,w1
                mov.b   #0x78,w2
                mov.b   #0x9A,w3
                mov.b   w2,[w1]
                mov.b   w3,[w1]
                mov.b   w0,[w1]
                mov.b   #0x42,w0                ; value to put into OSCCONL
                mov     #OSCCONL,w1
                mov.b   #0x46,w2
                mov.b   #0x57,w3
                mov.b   w2,[w1]
                mov.b   w3,[w1]
                mov.b   w0,[w1]

Well, since I wrote 0x42 to OSCCONL, I cannot communicate with the dsPIC via MPLAB ICD2 anymore.

The o'scope shows the chip works good (the firmware makes a pin toggle), but it now doesn't communicate with the ICD2 anymore.

What can I do, short of desoldering the chip and placing a new one in its place?

But how can a stupid software instruction turn a chip into deafness?

Thanks.
--
Electron

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