OESF Portables Forum

General Forums => General Discussion => Topic started by: bam on December 23, 2005, 11:30:18 pm

Title: Thermal Sensor
Post by: bam on December 23, 2005, 11:30:18 pm

I was thinking does the pxa270 have I2C? or perhaps a serial input(Basic), I program pic's and have the capability to do I/O operations and I2C/OneWire type thermal sensors, and I have a few(free samples from Dallas Semiconductor)

point being, it would be nice to see how warm the 3100 gets during operation and whatnot. The pic's are small enough to fit inside(at least the smt ones are, and they operate from 3-5vdc, with very small power requirements.

The only thing I am worried about is the software side, the hardware/programming side to the pic is easy.

Any thoughts ideas or suggestions?

Title: Thermal Sensor
Post by: Da_Blitz on December 24, 2005, 05:43:30 am

Linux has good i2c support for sensors, espesially the "lmxxx" range, however finding the pinouts and if the pins are avalible to use would be a diffrent matter, it would probely be better to hang a pic off the ttl level serial port off the back internaly and use a pic to translate between i2c and the serial port

the pxa270 does have a i2c port that can be used in client or host mode (cant rember the terminoligy, care to correct this) that could be used (meaning it can be a device on the network or a master that initiates communication

have you looked into the pxa datasheet as to wehter there is an internal tempreture sensor?, if it does have one it may be connected as a coprocessor

Title: Thermal Sensor
Post by: bam on December 24, 2005, 11:02:50 am

hmmm, no but I guess I should. I figured if it was possible someone would have done it already.(the internal thermal sensor)

Title: Thermal Sensor
Post by: Da_Blitz on December 25, 2005, 08:29:10 pm

The xscales do have a coprocessor to detirmine processor performance (ie cach misses cpu load and the like) however after glancing over the data sheet it dosent appear to have a built in temp probe

if it did it would be somthing that would be overlooked by most people

Title: Thermal Sensor
Post by: seinfield on December 29, 2005, 02:05:31 pm

The Sd interface is like a I2C.
You can emulate an SD card, make a program that reads the firts bytes of the SD (sd emulated with a microprocessor like an AVR or Microchip) and these numbers will be your temp. You only need to update these bytes.

Title: Thermal Sensor
Post by: bam on December 29, 2005, 07:36:06 pm

then I could make a script to remount the card after I cange the icon to one that reflects the temperature, this will be interesting, provided I can put all the steps together.

Title: Thermal Sensor
Post by: Da_Blitz on January 01, 2006, 09:38:40 pm

actually its more like an spi bus (in fact mmc emulation is done as an spi bus)