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Category Archive for 'Tinkering'

Ever wanted to know how to reduce the power consumption of your Atmel microcontroller when it’s not doing anything? The 2 videos below will step you though how you can reduce the power consumption of your Atmel microcontroller (in this case the ATtiny85) by using the power down sleep mode with the Watchdog timer.

The beauty of the watchdog timer is it allows us to not require an external interrupt to wake up the microcontroller, instead it wakes up after a certain amount of time by itself.

Link to the modified example for ATtiny85: ATtiny85_watchdog_example
Power consumption calculator: http://oregonembedded.com/batterycalc.htm
ATmega168 Sleep Watchdog website: http://interface.khm.de/index.php/lab/experiments/sleep_watchdog_battery/

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So I’m playing around more with the Scanalogic 2 Pro and thought instead of just reading the Logitech LX310 receiver’s EEPROM I would actually probe it and see what’s going on when it starts up. My plan for this post is to make it as simple and easy to follow as possible.

As you might know it’s a ST 95160 16Kbit EEPROM which is uses SPI protocol; I’ve found that SPI is harder to understand and use than two-wire (I2C) protocol. I used the Arduino SPIEEPROM page to assist me as well as the datasheet which once you read parts of it enough times and see what’s happening in the logic actually starts to make sense 😛

Download the complete timeline of SPI communication here: Logitech LX310 Reciever SPI 10Mhz
You’ll need to download the Scanalogic software in order to use the above file. Please note that the ms timeline shown in these pictures may be different to the timeline you download, however all queries are still the same.

Here is an overview of the first 10ms upon connecting to my computer.

What I suspect we see up to the first millisecond is the chip in the receiver is initialising itself by looking at the CS line as it’s going high and low very quickly, plus it could just be the rush of power to it causing the CS to go all funny.

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I thought I’d look into reading data from an EEPROM that is I2C capable from a PCB, the PCB is from a KVM which is a device that allows you to use your keyboard, video (monitor) and mouse on different PCs without switching out the cables.

Below is the PCB and the EEPROM which we’ll be looking at.

If you can make it out it’s a Atmel 24C32A, a 32Kbit EEPROM, datasheet here: atmel 24c32a

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