multiple props

ThePenguinMaster

ok guys i know this has been run into the ground over and over and over, but in risk of repeating a previous thread...

im planning on using a few prop chips for my project, getting them to work togather dosnt seem like a huge challange since one will be commanding the other as a hard drive controller, and buffering data to remote memmory. the part im unsure about is that i heard that 2 devices can be programed on one line using the i2c lines. is it possible to send programs to a chip and have both of them programmed in one run? how would one set something like this up?

Mike Green

Nothing is set up to be able to program two Props together. Neither the Propeller Tool, nor the boot ROM routines, nor the hardware. I wouldn't call it impossible, just impractical. You could use a switch to share the serial port between two Props, but that's not what you're asking.

Post Edited (Mike Green) : 7/17/2007 2:00:54 PM GMT

Peter Jakacki

One idea I have had is to daisy chain props off the parent prop so that each child's reset line is controlled by the preceding prop. The parent propeller is connected normally and is the one you talk to when downloading software. A pin from the parent goes to it's child's reset pin with a pulldown resistor to make sure the child always stays in reset until the parent can "speak".

When Prop 0 has loaded it's program from eeprom it can increment a predetermined "prop_number " variable in eeprom that starts at zero so as to enumerate each prop that subsequently loads from eeprom. Each prop just increment the prop_number and from there determines the software that it should run and of course releases it's child's reset line.

This also means that the eeprom may not be available for shared application memory unless some sort of bus busy detection is built in. Fortunately the I2C bus is designed for multimasters it just means that the I2C driver has to be up to scratch too.

Any existing prop design can easily be "multiprop'd" by piggy-backing another prop (dip or qfp) on top of the parent and simply bending the reset line out so that it can be wired to the parent's "child reset" line. Sounds too easy? Yes it does, but it is easy. Of course, the only I/O that needs to be shared are the I2C lines plus a dedicated child reset.

There are many variations of this basic scheme but it provides a very practical way of connecting and programming multiple propellers.

*Peter*

ThePenguinMaster

hey thanks for the tips. i just think it would be a cool ting to be able to update the software on two chips at once instead of switching the prop plug. ill work on a few different things. maybe one program can be loaded into the first master· prop and that one programs the seccond. or something like that.. i guess another option is to just keep it simple and do one at a time.· debug one and then work on the next. but im not that good of a planner where i can compleatly set up one to run the other without any problems lol. you can include a file to be sent with the program right? like if you wanted to send picture data with the program? maybe i can do that but with another program for the seccond chip.. hmm..

Mike Green

There is a downloader written in Spin that was posted on the forum a long time ago. I don't have a link to it, but search for "Propeller Loader".