Rob Guyatt

SH8 and ADC

Discussion created by Rob Guyatt on Aug 21, 2008
Latest reply on Sep 7, 2008 by Rob Guyatt
Having strife with ADC operation in the SH8 running at Vdd = 3V. I have a few other SH8 applications running ADC with identical configuration settings and no problems. All developed with Cyclone Pro and ICDHCS08. But the others are 5V. Even though in each application Vdd is not supplied via Cyclone Pro the appropriate Cyclone voltage level is selected.
The problem is the application stops responding up after a short time (seconds) . Halting operation within ICDS08 shows that coco,adcsc1 bit is not setting so it is staying in the loop
"adcloop   brclr    coco,adcsc1,adcloop"
All mcu configuration registers are default except for no cop and adc is 10 bit. The application also stops operating as above if it's started manually (not via ICDS08) but while still connected to the cyclone pro via the bkgd line and gnd. No reset line or vdd. In all cases mcu vdd is supplied separately and not via Cyclone Pro.
To get the mcu to run without failing I just disconnect the bknd line from the Cyclone and restart.
As mentioned, the only difference between this application and others that don't give trouble is that this is a 3V application.