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Re: H8S 2674R All Module Clock Stop Mode??

We are using a Renesas H8S 2674R processor and cannot get the

>specified current consumption numbers when entering the All Module >Clock Stop mode. Has anyone successfully used this mode in this family >of H8S processors?

Due to other tasks [real life] I forgot to follow up to this before.

You are of course remembering that most standby modes retain the I/O port status so a HIGH output causes NO reduction in current consumption for that pin. I suggest you check what the I/O pins are doing when you enter that standby mode.

This is described in the manual on Power Down modes and is the first item in the Usage notes (see in conjunction with Table 22.1 Operating Modes for what each module actually does).

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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Reply to
Paul Carpenter
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Thanks for the reply. I built up a board with only the processor and a FLASH chip, and I sent the device to all module stop immediately after reset (i.e. all pins were inputs). This still did not give the specified current value. I then configured all I/O pins as outputs and drove them low, and modified the bare board to tie all input only pins low. I then did extensive testing with all module clock stop vs. software standby, setting and not setting the OPE bit in the sbycr register. With the OPE bit set all output pins are maintained when going to software standby as they are in all module clock stop. Our results showed that in software standby we got the expected (specified) current consumption (On Thu, 31 Mar 2005 00:46:06 GMT, in article

Reply to
Dave Madsen

What else is connected (pull-ups, serial converters etc..)? Just a thought, because you must be getting the code in there somehow.

Done all the things I would expect to test. However I note that if you are having the clock output going, that circuit will draw current and depending on what it is driving could effect the current drawn.

Have you tried this with the clock output not loaded or disabled? Have you tried this without the external flash?

I assume you are stopping the 8 bit timer and I assume you are not using the WDT as well.

I personally have not used that particular device but various H8 devices. I would have thought others here may have had something to offer on the subject.

You might also get some assistance from others on the GNUH8 mailing list (see signature block). I would also suggest talking to your distributor to get from Renesas the test circuit they used to get the figures which in my datasheet have a note "The values are for reference" against the curent consumption figures. This seems a bit of specmanship to me which would need ratifying by Renesas to get what they mean by that.

--
Paul Carpenter          | paul@pcserviceselectronics.co.uk
    PC Services
              GNU H8 & mailing list info
             For those web sites you hate
Reply to
Paul Carpenter

The FLASH chip is in a socket, so we program it out of circuit. We do run Rx and Tx to another board with RS232 drivers, but these are disconnected and disabled for the current measurements.

No pull-ups on the bare board.

I have set and cleared the PSTOP bit, which disables and enables the phi clock from being fed out. This makes very little difference on the current consumption of the bare board. The fact that the current is very low with software standby (regardless of the setting of OPE) and not with all module clock stop seems to eliminate the FLASH chip.

Correct, all of the peripheral modules are unused.

Thanks for your suggestions. We are working with our Renesas Rep and he has been in contact with Renesas, it is slow getting answers from them, but they say that the numbers are real.

Reply to
Dave Madsen

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