8-bit MicrocontrollersのトピックM68DEMO908GD60, Low power and RS232

M68DEMO908GD60, Low power and RS232

vga — Fri, 13 Oct 2006 20:46:41 GMT

I'm a new player on this field, so please excuse my newbie quiestions.

I have a M68DEMO908GB60 board and I'm writing an app that needs low power but still being able to response to commands through RS232 periodically.

After reading the documents it is my understanding that my only option is to use the 'wait' command and none of the stop modes?.

I think I have initilized all the I/o's correctly to what is needed and those not needed but still I'm seeing too much power usage in the +20ma region.

example I/o pins init port :

setReg8(PTBD, 0);

setReg8(PTBPE, 255);

setReg8(PTBDD, 0);

init code:

SOPT = 34;

SPMSC1 = 0;

SPMSC2 = 0;

ICGC1 = 60;

ICGC2 = 112;

I'm thinking that I must be forgetting something or tottally misunderstanding how I should set up the board before starting, So my question is, has anyone here done a similar thing and has some tips on how I should set up this board to get absoulute minimum power usage at wait?

Re: M68DEMO908GD60, Low power and RS232

bigmac — Fri, 13 Oct 2006 22:14:54 GMT

Hello,

I am not clear on the MCU you are using. Is it the 9S08GB60?

You will need to consider the current draw of other devices on your board - some of the unused devices may be consuming power.

The on-board voltage regulator may not have low quiescent current.

Are there instances where pull-up resistors external to the MCU, and associated with jumpers or selector switches, are drawing current.

At risk of stating the obvious, does the board have any LEDs that are operating?

The device used to interface RS232 levels may not be of the low power type. If there are two serial ports, the interface associated with the unused port may be drawing current.

Any output line for the serial port will need to supply current back to the PC. Unplug the serial cable, and see if the current reduces.

These are a few of the areas that would need to be checked and quantified before you could conclude that the problem was with the MCU.

Regards,

Mac