Archive for the ‘Uncategorized’ Category

New Tricks for Lower Power from Atmel

Thursday, April 23rd, 2015

There has always been a trade-off between high performance and low power. Nowadays, microcontroller makers try to combine high performance while running with low power when idle.

The Cortex-M0+ processor core from ARM is claimed as their “most energy efficient”, and forms the basis of a number of recent microcontroller products.

Atmel‘s SAM D20, D21, and R21 feature the Cortex-M0+ core – and we have been working with these for a while:

SAM D21, R21, and D20 Xplained-Pro Boards

SAM D21, R21, and D20 Xplained-Pro Boards

Recently, the nice people at Atmel have kindly sent us an early example of the new SAM L21 Xplained-Pro board – featuring their latest, lowest-power addition to this range – the SAM L21.

Atmel SAM L21 Xplained-Pro board

Atmel SAM L21 Xplained-Pro board

Two New Tricks added in the L21 to allow it to achieve even lower power levels than the D21 are:

1. Powering-down unused modules

The D21 allows module clocks to be stopped, to reduce dynamic power consumption – but this still allows leakage currents to flow. By cutting the power, the leakage is greatly reduced.

2. Variable core voltage

The L21 has two “performance levels”: at the lower level, the core voltage is reduced to save power but with limited execution speed; the higher level allows maximum speed, but consumes more power.

Of course, all these features are to no benefit if the application doesn’t make best use of them – and doing that can be no mean feat!

To aid in optimising the system power consumption, the L21 Xplained Pro board features the Xplained Pro Analogue Module (XAM) to enable current consumption to be measured via the on-board debug interface (EDBG):

Xplained Pro Analog Module (XAM)

Xplained Pro Analogue Module (XAM)

Well, that’s enough writing for now – time to go off and give it all a try…

Identifying a Modem’s COM Port in Windows-XP

Thursday, September 15th, 2011

Windows usually communicates with a modem via a COM Port interface – whether that’s a “real” serial port, or a “virtual” serial port for an integrated modem or via USB.

To find what COM port Windows is using, start by locating the modem in Device Manager:

Device Manager

Right-click the required modem in the list:

Modem right-click menu 

Choose Properties to open the modem properties:

Modem Properties - General

Now choose the ‘Modem‘ tab:

Modem Properties - 'Modem' Tab

Note that the Port is identified at the top of the panel – in this case, it’s COM3.

Hot Tips for Cold Starting

Tuesday, November 30th, 2010

The cold weather is with us again here in Southern England.  Well, we call it “cold”;  others may differ – including those further North in the UK!

First snow of the 2010-11 winter

These conditions put extra strain on a car’s electrics, and can lead to starting problems. 
So here are some Hot Tips for Cold Starting:

The important thing to remember is that, once the engine has stopped, there is nothing putting any power into the battery – therefore anything electrical at all that’s left on after the engine’s stopped will be flattening the battery.
So the first tip is:

Before you stop the engine:
Be sure to turn off everything electrical; lights, demister, blower, etc.
Close electric windows before stopping the engine.

The second tip is the converse of the first:

Do not switch anything on before the engine has started. 
Start the engine as soon as possible after turning on the ignition – don’t wait with just the ignition on unless the car requires it(check handbook for details; eg, a diesel with glowplugs).

Tip for cars with manual transmission:

Depress the clutch pedal (“let the clutch out”) while starting.
This reduces the load on the starter and, hence the battery – thus increasing your chances of starting successfully

If you do need a “jump” start, remember that modern cars have lots of electronics in them; therefore be very sure to follow any directions in the handbook to avoid damage. If in doubt, leave this to a professional assistance service.

Do not be tempted to “jump” start a car using a so-called “Leisure” battery – as used for camping, caravans, etc. These are just not designed to give the huge “kick” required to start an engine (especially a diesel), and are likely to be damaged by it. (If you have a freshly-charged leisure battery, connecting it to the car battery for 5-10 minutes might charge the car battery sufficiently for a start; but be sure to disconnect it before starting and, again, follow any handbook directions).

Final tip, after a “jump” start:

Take the car for a good run – say, 15-20 minutes.
The reason you needed a jump start was that the battery was flat; if you don’t take steps to ensure that the battery gets well charged, the same will happen again!
More charge is generated at higher engine speeds (within reason), so the “open road” at “cruising speed” will be better than around town, if possible.
It is not recommended to leave the engine “idling” for long periods, nor to “rev” it while stationary. Again, be sure to follow any directions in the handbook to avoid damage and, if in doubt, seek professional advice.

Of course, if the car has persistent starting problems, it should be checked for faults in the battery and the charging and starting systems. Remember that batteries have a finite life.

Disclaimer: This post is presented in the hope that it may be of some use and/or interest; it is given “as-is” and entirely without any warranty of any sort whatsoever – any use of it is entirely at your own risk. If in doubt, seek advice from your vehicle provider, maintainer, or other reputable source.

Modem Diagnostics in Windows-XP

Friday, October 15th, 2010

Windows-XP (among others) can maintain a log of all commands sent to a modem, and responses received from a modem. This can be very useful in diagnosing problems with dial-up networking, etc

Start by locating the modem in Device Manager:

Device Manager

Right-click the required modem in the list:

Modem right-click menu 

Choose Properties to open the modem properties:

Modem Properties - General

Note that the Troubleshooting button here is not what we want – instead, go to the Diagnostics tab:

Modem Properties - Diagnostics

Check Append to log to enable logging of all commands sent to the modem, and all responses received from the modem.
The View Log button, as the name suggests, can be used to view this log (note that it’s just a text file – once you know where it is, you can view it with any application you like)

The Query Modem button sends a number of commands to the modem, and captures the responses (if any).
While this is happening, the following message is displayed:

Modem Diagnostics - Communication in progress

When complete, the commands sent & responses received are shown:

Modem Properties - Diagnostics (with responses)

These will also have been recorded in the log – press the View Log button to see:

Modem Diagnostic Log

(for details of the commands and responses and their meanings, you will need to consult the particular modem’s documentation).

Now, as long as you leave the Append to log option checked, all commands sent to the modem, and responses
received from the modem, will continur to be recorded in the log. Therefore, if you get any error messages from Dialup Networking, etc, you can look at the log to see exactly what happenned…

Note that the log only records modem commands & responses in creating and clearing connections – it does not record the data passed through the modem once the connection is established.

Happy New Year!

Saturday, January 9th, 2010

Welcome to 2010!

This is the first time in around 30 years that we’ve actually had a white Christmas here in South-East England:

White Christmas?

I wonder what other surprises the year will hold…?