New guy would like to bother you about SPI and the AD5206 a bit.

Hello all! I have just registered on the forum but I have been playing with the Arduino platform for a few weeks now. So far I have done everything using the i2c bus, but now I would like to experiment with the AD5206 digital potentiometers used in the SPI tutorial. So, to get to the point, here are my questions.

1.) My project calls for many more than 6 channels. How many AD5206 chips can operate on the SPI bus? I have tried to find information about device addressing like i2c has but I have come up empty.

2.) Is there a chip similar to the AD5206 that is compatible with i2c? So far I have not been able to find one.

3.) I can use i2c devices and SPI devices on the Arduino at the same time correct? They should not interfere?

Thanks in advance for the replies. Mike

Each SPI device as an SS pin, SS means Slave Select, so you can have as many SPI slaves as you wish, if you use an shift-register, you can have dozens of SPI slaves, or more.

Yes, you can use SPI and I2C devices, they have totaly different pins.

The AD5259 is a similar part with an I2C interface. On the SPI parts, if you drive /CS high, the part is not addressed. You would use a separate /CS pin for each part. Yes, you can mix I2C and SPI on the same Arduino.

You can get an IC (e.g. 74138) to chip select 8 parts from just 3 pins if you need more.

Thank you both for the replies! The AD5259 isn't exactly what I am looking for, but the information provided on SPI makes me more comfortable with the AD5206.

So let me review to make sure I am understanding properly. Each CS pin must have a connection to the Arduino and they are normally driven high? And to address a certain chip you bring it low?

http://arduino.cc/en/Tutorial/SPIDigitalPot hmm, that seems to be what is explained here actually, but I didn't catch it.

"Each CS pin must have a connection to the Arduino and they are normally driven high? And to address a certain chip you bring it low?"

Yup.

Excellent! I'm all ready for another Mouser order! :grin:

Yep, next thing you know you'll be getting carried away too ...

www.crossroadsfencing.com/BobuinoRev17

That scoring machine is really cool!

What did you use to make the PCBs for the Bobuino? The toner transfer method? I have not attempted custom PCBs before.

Thanks :)

I designed the Bobuino in Eagle, then bought 10 PCBs from iteadstudio for $29.90 (and they delivered 12!) The board is way too complex for me building. The cost of double sided board material, ferric chloride, time drilling holes, lack of vias for traces, lack of silkscreen, lack of solder mask, all adds up to just make having them made commercially a no-brainer. They have lower prices for smaller boards too. I have made plenty of wirewrap boards, if I want something complex quick I will do that (gives me a lot of flexibility to tweak the design as I go to suit parts on hand, I can build up a board like the 2 below in a day - one with a Promini, one with similar parts but a standalone Atmega328), but for $29.90 for a larger board in more than qty 1 I'm definitely thinking commercially made PCB.

The larger box started out as reading a serial port for touches, and I added MAX7219 to drive 8-digit display, then RF Rx for RF remote, then added 2nd Promini to do the touch detects (needs 6 I/O pins, the evolved design had run out of pins). These are control boards for a smaller scoring machine, detects touches but does not have Score/Time. The design is most of the larger one, without the MAX7221 to drive the 8 digits or the RF Remote receiver. With my ATMega1284 experience, I think I'll now do a PCB that can be used in either box as it provides enough IO to everything - and add some other features that the extra pins and larger memory can support.

Wow. I am surprised at how cheap those PCBs are. The site says that they are for prototypes but would you rate the quality higher? When I started this I have been gathering information on getting PCBs made and custom drilling and cutting on enclosures and such and I am consistently surprised by how cheap it all is. Imagine if you built a RepRap! Super cheap parts!

You’re saying that this thing detects points made during a fencing match? :astonished:

Also, I am so glad that the internet exists so that I can get advice and such from people with much more experience than I. I can’t imagine getting started with this without the wealth of info available online. I think we are spoiled :slight_smile:

Zepp,
Yes, the boards seem to be very good quality. I am very pleased with them.

Yes, my boxes detect touches made during a fencing match. I have the 1 main box, it connects to two remote boxes that are just lights.
I have 5 of the simpler boxes that also talk to a remote light box.

Spoiled, yes, probably so 8)

That is awesome. XD