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FEZ Mini with SD21 Servo Controller


#1

Hi Folks.
I have a SD21 servo controller. One of its nicer features is that one can plug in a Basic Stamp, so that also means I can use a FEZ Mini and get a lot more processing power.

I’mm prob will have to do a little rewiring if the I2C pinouts are not the same.

Anyway - I was wondering if anyone else has used this board.

Its uses I2C and cone can offload the servo housekeeping positioning, and speed of servo movement onto the SD21 leaving the FEZ for lots of other more important work.

My longer term project is a self contain animatronics system that can read sequences off an SD card and then send them to the servos. To create a smoothing effect I pland to read the sequences every 250ms, so I can easily program slow and fast movements.

Really looking forward to getting my FEZ Mini - should be hear in a couple of days.

Take Care
Dave


#2

BS2 had I2C?! Probably simulated in software?

I can’t see why FEZ wouldn’t work on there but please if you try it then let us know how it goes.


#3

Hi Gus

It seems so. They mention the BS2p Stamp and it does have an I2COUT command.

Here is the link to the SD21 and it has BS2p and PicAxe code samples there too.
http://www.robot-electronics.co.uk/htm/sd21tech.htm

Looking at the pinouts… the BS2p uses pins 5 & 6 for its SDA/SCL where the FEZ Mini uses pins 9 & 10. So I willl need to do a little rewiring on the SD21.

Many thanks for the quick reply too. I’m looking forward to being a contributer here with some of my projects.

Previously I have used PicAxe’s and will continue to do so for small projects that don’t need much processing power and use the FEZ range where I’d use Arduino’s.
With the current project I’m planning to use an PicAxe 20X2 as a A/D converters I can let it gather the data so I can then read it using I2C with the FEZ. That way the FEZ can do its main work as the overall controller.

Take Care
Dave


#4

You do need second micro for reading analog. Try fez and you will see what I mean


#5

Oh I understand I could use the FEZ, but I’m a little unsure re the speed that the FEZ does an A/D conversion.

I have an important process that needs to be completed every 250ms. I’d prefer that the FEZ not be kept waiting to do the A/D hence offloading it onto an PicAxe 20x2.

The 20X2 can be configured to have 11 A/D’s and be a I2C slave. That way it can just slog along doing the A/D and I can read the results when I need them. I already need to monitor 8 A/D’s.

My FEZ will also be reading from an SD card, chatting I2C to the 20X2 and the SD21, as well as talking SPI to a MAX7456 board so it could be a bit busy. Plus the FEZ Mini does not have a lot of pinouts and I don;t have the space to go larger.

Many thanks for your thoughts and replies.
Dave


#6

Yes fez can probably do all that :slight_smile: just give it a try before you think about adding a second micro

My dot said do but what I meant is don’t lol