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h8/3337 port 3 problem

hello, I know such a topic may sound a little out of date.... sorry...

I'm reworking an old H8/3337 based project, the processor is in mode 3 (single chip mode)..

the problem I have regards PORT 3 BIT 3, I can't switch it from output mode (P3DDR.3 = 1) to input (P3DDR.3 = 0)

according to the datasheet, this pin should act as a general purpose I/O pin in mode 3, if the corresponding bit is cleared in the DDR register, this should put the pin into hi-impedance state and the actual state of the pin should be read by reading the data register...

What happens to me is that the output never goes to hi-impedance, though the actual state of the pin can be read...

P3PCR (Pull-up control register) is OFF

The DDR register is a write only register, according to this restriction I never read it, I simply switch the bit 3 from output to input by just writing 0xFF to DDR first, then writing 0xF7

I have no idea about what's wrong, I write firmware since 30 years, I found no application note or errata corrige on this ancient controller....

any help please?

Reply to
la_panza
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Yes as long as you do NOT have host interface slave data bus mode enabled (SYSCR.HIE = 1 should be 0).

Suggests a mode fault or SYSCR problem.

It could just be possible you are looking at the wrong line. I have been caught by this before now and kicked myself (repeatedly).

That is my quick look thoughts.

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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Reply to
Paul Carpenter

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