Non dallas 1-wire devices

barl

Hi, new to the forum but somewhat familiar with programing mostly industrial controls.
I purchased 8 , 1-wire 7-segment displays from sparks fun (part# com-09763) thinking I could string them all together on the Bs2p 1-wire buss pin. to display readings from various sensors, some of the sensors are Dallas 1-wire devices (DS2760 thermocouple modules) + additional analog sensors.
The problem I am having is that the sparks fun LED display control chip ( ATMega328) is not programed with a serial number to identify which display to send any one of the sensors readings to .
I e-mailed and called sparks fun, seems there all arduion fans and said it was possible with newsoftserial on the Arduino platform but had no clue if stringing the displays togeather on the Bs2p could be done. below is there response,

response 1................The 7-segment displays do not have serial numbers. Let me know if you have any other questions.

response2..........I wasn't able to find any info how to have multiple serial devices using the Basic Stamp. I asked around in our Engineering department and no one really used Basic Stamp here either. It seems like you will need to write a software serial implementation. (Kind of like NewSoftSerial for Arduino) I recommend going on the Parallax forums to see if the community members have hints. The Parallex support team would have the best idea who to do this. Sorry that we don't have a better answer for you!

without a serial number to point to i don't see how I can run more than 1 these off the 1-wire buss, the only solution I have been able to see is running them off of pins 1-8 with multiple serout commands but haven't tried it yet and that eats up more pins than i would like.

anyone out there have any idea what my best solution would be or how to tag these displays individually,
thanks,
[h=3][/h]

Mike Green

First of all, these are not "1-wire" devices. They happen to use a single control line, but they use ordinary asynchronous serial communications which is completely different. SparkFun has added an ATMega328 controller and you would have to write a new control program that supports some kind of addressability. That would be the only way to "tag" these displays so they're addressable. SparkFun does provide the source code for the controller, but you'd have to work out your own modifications.

It would be possible to use external devices, like a decoder (a 74HC138 for up to 8 devices each). This would take 4 I/O pins plus one for each group of 8 displays. If you need more than 24 displays, you could always use another 74HC138 to select one of the other 74HC138s and need only 7 I/O pins for up to 64 displays.

barl

Thanks Mike, I was afraid of that seems I jumped the gun on that purchase, I guess im stuck with using 8 pins on the Bs2p to make it work, should have gotten the 40 pin version, live and learn
thanks for the prompt reply, This forum is very helpful and informative.

Mike Green

With the 74HC138, you'd have to connect Vcc and Ground of course and use a 0.1uF ceramic bypass capacitor across Vcc and Ground. Y0 through Y7 would each be connected to a display (see Figure 2 of the datasheet). A0 through A2 would be connected to BS2p I/O pins to select which display to use. CS1 would be connected to Vcc. CS2 would be connected to Ground. CS3 would be connected to another BS2p I/O pin and used for the SEROUT. You'd want to initialize the CS3 I/O pin to HIGH and the A0-A2 I/O pins to LOW. You'd set A0/A1/A2 to select which display to access, then do a SEROUT for that display using the CS3 pin.

barl

That sounds like a viable solution I'll look into it, really wish sparks fun didn't advertise these as 1-wire devices though or maybe my fault for not distinguishing the differences before hand..to bad Dallas doesn't have these.
thanks,