lots of Inputs??

oRiCLe

Hello, i have been looking into these chips and doing some research for some time but i have not found any details on the following few points if someone can fill me in as i am currently doing research to provide a computerisation for an industrial saw and require some measurement readings etc...

- Approx 10-15 analog inputs, 0-5v and at least one 0-24v line
- Approx 10-15 Digital outputs for relays
- VGA/TV monitor + keyboard to manipulate the saw
- SD reader/writer to read in settings and write out a log/counter for statistics later
- Bluetooth/RF to control the saw or send info back to a computer

could someone please maybe suggest some ways that the 8 lines could utilise such equipment and if it is possible to have this many peripherals hanging off the propeller chip. thanks.

mirror

If you start with a chip - and not the demo board - then you could easily design something like this with the correct peripherals. My current design has :
24 Analog Inputs - 0-5v - 12 bits
8 Digital Inputs
8 Digital Outputs
10Mbps Ethernet Chip
SD Interface
3 Bi-directional serial ports
Real time clock with extra RAM and battery backup
32K of extra EEPROM

So what you want doesn't seem to be a huge challange, but not easily done with the demoboard as is - you would have to add quite a bit of multiplexing to those 8 pins.

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It's not all that hard to count the number of grains of sand on the beach. The hardest part is making a start - after that it just takes time.·· Mirror - 15 May 2007

oRiCLe

wow! sounds good, do you have any schematics more info on your design? maybe even a piccie [noparse]:D[/noparse] sounds just like what im after...

Graham Stabler

the proto-boards also give full access to all the pins too. The main issue is the analogue inputs but you could get a multichannel ADC chip with serial interface perhaps.

What kind of a saw is this?

Graham

oRiCLe

its a timber saw for cutting house frames and recessing areas for noggs etc and trusses cutting angles etc, it has pneumatic clamps, chain driven slides, and full 3 axis saw head.

Graham Stabler

Cool, I saw something a bit like this on an episode of "grand designs", the guy ordered a custom built house from Norway or somewhere like that and it came on the back of a lorry like a kit. They showed the factory and they had some super cool machinery to make the joints and ensure it all locked together.

What are the analogue inputs for? Are you just wanting to be able to display the values or act on them?

Graham

Mike Green

Graham has a good idea, using a Protoboard. That gives you the keyboard / VGA connections already. You could use a MatchPort (www.lantronix.com/device-networking/embedded-device-servers/matchport.html) for WiFi connectivity or some kind of Bluetooth module. Another option would be ZigBee (en.wikipedia.org/wiki/ZigBee), using an xBee module (www.selmaware.com). The TPIC 6595 from TI is a very nice 8-bit I/O expander for driving relays. They can be cascaded and require only 3 or 4 I/O pins (shift in clock, data, transfer shift register to output register, reset). The SD card interface just requires a socket and 4 I/O pins. The analog inputs could be done with any serial (SPI) multichannel ADC (www.maxim-ic.com/) using 3 I/O pins. If you need more than one, 2 of the I/O lines can be shared. A 0-24V input can be converted to a 0-5V input with a simple voltage divider.

DavidCary

Can I feed 4 independent SPI ports into the propeller?

Like oRiCLe, I am also putting together a couple of projects with lots of ADCs.

Some MCP3208 serial 12 bit 8 channel ADCs.
Some ADS1271 serial 24 bit 1 channel ADCs.

I originally thought I needed lots of CPUs.

But I suspect I can daisy-chain the serial ADCs into several chains,
then feed several chains into independent SPI ports on one propeller.

My questions about speed were answered at
http://propeller.wikispaces.com/interface

Thank you for telling me about the TPIC6595 8-Bit Shift Register, 0.25 Amp output.
It will probably replace a 74HC595 eight bit shift register, plus an array of transistors, in one of my designs.
( http://opencircuits.com/POV_display ).

Mike Green

Yes, you can feed multiple SPI devices from a Propeller. You can either use completely separate I/O pins for each device or you can share the data (DIN / DOUT) and clock (CLK) pins and have separate chip select (CS) pins. With separate I/O pins, you can use a cog for each device and do high speed I/O simultaneously. With shared pins, the SPI devices have to take turns.

RinksCustoms

I'm working on a prototype that can give up to 45 free I/O's, onboard keyboard, mouse, video, and 8 & 12 bit ADC's. I'm not including the PS2 game controller interfaces to speed up design time. I'm currently working on the PCB layout and trying to keep it a 2 layer compact board to keep the price down.

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E³ = Thought

http://folding.stanford.edu/·- Donating some CPU/GPU downtime just might lead to a cure for cancer! The average PC while browsing the internet typically uses less than 30% of it's potential, why not donate a portion of the rest for cancer resaerch?

OakGraphics

Rinkscustoms - would be interested in your board. what chips are you putting on it to give you the extra i/o and adc? Will you have onboard USB for programming?