It's maddening. Such a simple project. I have a 16F627 supposed to
drive some transistors with a pulse. The scope shows the port B
outputs are low at rest, as they are supposed to be. But when they
are commanded to pull high, they seem to go tri-state instead. The
scope shows the lines float, with 60 cycle noise, for the duration of
the supposed high state (.01 seconds). Then they return to a low
state.

How can this be? The TRIS register is not changed. They output a low,
but won't pull high. Even a spare bit, unconnected to anything,
behaves the same way.

The clockout pin shows the internal oscillator is running, and the
circuit works fine when emulated with the Mathias ICE. I've tried
several chips.

--

Bryan Mumford
Mumford Micro Systems
bryan@bmumford.com

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