9S08QG8 bandgap giving unexpected readings

取消
显示结果 
显示  仅  | 搜索替代 
您的意思是: 
已解决

9S08QG8 bandgap giving unexpected readings

跳至解决方案
1,544 次查看
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
标签 (1)
0 项奖励
回复
1 解答
763 次查看
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

在原帖中查看解决方案

0 项奖励
回复
1 回复
764 次查看
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
0 项奖励
回复