9S08QG8 bandgap giving unexpected readings

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9S08QG8 bandgap giving unexpected readings

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tonyp
Senior Contributor II
Hi all,

I have this issue with a QG8 (actually I tried with several).  While it measures 3.287V on the chip between Vdd/Vss, reading the bandgap channel (27)  with 10-bit A/D gives 200 (decimal).  If I understand how the bandgap works, this indicates an operating voltage of 6.138 assuming typical 1.2V bandgap (Vdd=1023*1.2/ADBG)

Shouldn't I be getting a bandgap reading of about 375?

TIA


Message Edited by tonyp on 2007-12-13 02:54 PM
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tonyp
Senior Contributor II
Problem solved.  BGBE in SPMSC1 should be set from within code.  Setting it through the debugger, apparently doesn't work, even if your code never writes to SPMSC1.  Bandgap channel now returns 372.


Message Edited by tonyp on 2007-12-14 06:54 PM

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tonyp
Senior Contributor II
Problem solved.  BGBE in SPMSC1 should be set from within code.  Setting it through the debugger, apparently doesn't work, even if your code never writes to SPMSC1.  Bandgap channel now returns 372.


Message Edited by tonyp on 2007-12-14 06:54 PM
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