Home
JAQForum Ver 20.06
Log In or Join  
Active Topics
Local Time 15:56 19 May 2024 Privacy Policy
Jump to

Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.

Forum Index : Microcontroller and PC projects : Micromite CPU SLEEP

Author Message
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 05:09pm 08 Feb 2016
Copy link to clipboard 
Print this post

I am sure this has been discussed some time before but can some remind this GHOB (grey haired old b) how I can recover from this predicament:
Micromite 150 running 4.5E
Have edited the program to reduce power consumption with CPU SLEEP 1000 and AUTORUN is implemented. So as this was not available until 5.1 can I break the program without having to re-program the chip?
GM
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2294
Posted: 06:36pm 08 Feb 2016
Copy link to clipboard 
Print this post

shorting together TxD and RxD while applying power will do a factory reset. you could also try feeding the output from a signal generator into WAKEUP and hold down ctrl-C on your terminal and see if you can break out of the loop.

cheers,
rob :-)
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 07:18pm 08 Feb 2016
Copy link to clipboard 
Print this post

  robert.rozee said   shorting together TxD and RxD while applying power will do a factory reset. you could also try feeding the output from a signal generator into WAKEUP and hold down ctrl-C on your terminal and see if you can break out of the loop.

cheers,
rob :-)


Thanks Rob, but as it would be the case I have not saved the code so a rx/tx short will loose the programming.
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 07:20pm 08 Feb 2016
Copy link to clipboard 
Print this post

Success!!!!!!!!!!!!!!!!!!
Thanks Rob for reminding me. A ground on the reset pin combined with a CTRL-C did the trick.

Wonder what I can stuff up next.
GM
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 11:33pm 08 Feb 2016
Copy link to clipboard 
Print this post

I changed the 150 to 170 with 5.1 and issued the cpu sleep 3 in the program but the circuit still draws 4mA during the sleep period not the 80uA as suggested in the manual. I have stripped down the circuit to try and find where the current draw is. along with the 170 chip is a 100k/10k voltage divider to an analog pin, a LED via a 100R resistor unlit and the 3T 3V3 regulator.

Could the current draw be an overhead of the 3T regulator?

Any suggestions?
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2294
Posted: 12:27am 09 Feb 2016
Copy link to clipboard 
Print this post

what is the part number of the regulator? 4mA sounds about what i'd expect, assuming the regulator is nothing special.
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 12:40am 09 Feb 2016
Copy link to clipboard 
Print this post

Rob the regulator I am using is the L78L33ACZ dropping 5V to 3V3.
GM
 
Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3167
Posted: 12:46am 09 Feb 2016
Copy link to clipboard 
Print this post

Reducing the current drawn in sleep can be difficult. Any I/Os will continue to draw or source current so they should be disabled if you suspect that. Also, peripherals like the serial UART and SPI will draw current in sleep if they are open.

You can test the sleep current of the bare chip with nothing connected to its I/Os by running a program consisting of just the command CPU SLEEP.

Geoff
Geoff Graham - http://geoffg.net
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 12:58am 09 Feb 2016
Copy link to clipboard 
Print this post

  Quote  You can test the sleep current of the bare chip with nothing connected to its I/Os by running a program consisting of just the command CPU SLEEP.

Thanks for the input Geoff. I will strip out the program and report back with a measurement when I am back in the shed tomorrow.
GM
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2294
Posted: 12:59am 09 Feb 2016
Copy link to clipboard 
Print this post

  Graeme Meager said  the regulator I am using is the L78L33ACZ dropping 5V to 3V3


according to page 6 of the datasheet here:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00000446.pdf

the quiescent current is no more than 6mA. this would seem to be the likely offender! do you need to have a regulator at all? a micromite should be happy on a pair of AA cells directly.


cheers,
rob :-)
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 01:21am 09 Feb 2016
Copy link to clipboard 
Print this post

  Quote  the quiescent current is no more than 6mA. this would seem to be the likely offender! do you need to have a regulator at all? a micromite should be happy on a pair of AA cells directly.


Rob,
In this case the micromite is monitoring a 12 volt battery so that is why I would like it to draw as little current as possible. On the bench I am only feeding it with 5v from the USB-serial converter.
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2294
Posted: 01:55am 09 Feb 2016
Copy link to clipboard 
Print this post

you may wish to consider the LP2950-3.3 in that case, with a ground current of 120uA or less under light loads (according to the TI datasheet):
http://www.ebay.com/itm/181847005970
http://www.ti.com/lit/ds/symlink/lp2950-n.pdf

cheers,
rob :-)
 
WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2794
Posted: 02:14am 09 Feb 2016
Copy link to clipboard 
Print this post

I like to use the MCP1700 3v3 LDO for MicroMite circuits that 'sleep'.

They draw just 2uA so are ideal for battery circuits with the occasional 'processing' time.
Also conssider reducing CPU speed to as low as possible (but remember that some commands require a higher CPU speed).

WW
For everything Micromite visit micromite.org

Direct Email: whitewizzard@micromite.o
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2294
Posted: 02:29am 09 Feb 2016
Copy link to clipboard 
Print this post

  WhiteWizzard said   I like to use the MCP1700 3v3 LDO for MicroMite circuits that 'sleep'. They draw just 2uA so are ideal for battery circuits with the occasional 'processing' time


unfortunately the MCP1700 range of regulators have a maximum input of 6v according to this datasheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/20001826C.pdf


cheers,
rob :-)
 
paceman
Guru

Joined: 07/10/2011
Location: Australia
Posts: 1329
Posted: 03:55am 09 Feb 2016
Copy link to clipboard 
Print this post

The MCP1702-3302E (TO92) is supposed to be good for 13.2v input and the MCP1703-3302E/DB good for 16v input in the 4pin SOT223 package.
Edited by paceman 2016-02-10
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 12:33am 10 Feb 2016
Copy link to clipboard 
Print this post

I see that Jaycar has the LM2936 3.3v reg in their list. Would you think that that would be a good contender?
GM
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2294
Posted: 01:23am 10 Feb 2016
Copy link to clipboard 
Print this post

the LM2936 datasheet lists:
±2% Initial Output Tolerance
±3% Output Tolerance Over Line, Load, and Temperature
http://www.ti.com/lit/ds/symlink/lm2936.pdf

while the LP2950 datasheet claims "a tight initial tolerance (0.5% typ), extremely good load and line regulation (.05% typ) and a very low output voltage temperature coefficient, making the part useful as a low-power voltage reference".

given that the micromite uses the 3v3 supply as the analog reference, and that your application is making use of the analog inputs, the LP2950 would still seem to be the preferred choice.

i trust you are ok with ordering parts from ebay? it is extremely painless, you use paypal for payment - with a credit card you can use a guest paypal login. the whole process is extremely safe and takes just a minute or two to complete.


cheers,
rob :-)
Edited by robert.rozee 2016-02-11
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 11:24am 10 Feb 2016
Copy link to clipboard 
Print this post

  Quote  i trust you are ok with ordering parts from ebay? it is extremely painless, you use paypal for payment - with a credit card you can use a guest paypal login. the whole process is extremely safe and takes just a minute or two to complete.


Thanks Rob, I am OK with ebay ordering and have accounts with RS and Element14 just a bit impatient.
GM
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 911
Posted: 09:02pm 17 Feb 2016
Copy link to clipboard 
Print this post

  Quote  You can test the sleep current of the bare chip with nothing connected to its I/Os by running a program consisting of just the command CPU SLEEP.

Geoff


It has taken some time to get back to it but the 170 chip in sleep mode draws a whopping 56uA.
I have set the 170 chip to flash a high brightness LED for 1mS every second running on a 2032 button battery. It will be interesting to see how long it lasts.
GM
 
Print this page


To reply to this topic, you need to log in.

© JAQ Software 2024