AO Shield

I have a shield I was considering making. I want it to have a single Analog Output from the Arduino to another device.

Requirements: Work with multiple versions of Arduino's. (aka the 5V output and 3.3 V output arduinos) The voltage to the other device must stay in the range 0-3.3V I want to use the minimum number of pins to achieve this. I would like this to be low power.

Questions: What type of circuit would you use to achieve this and why? Which AO pin would you use and why? (I would like this shield to not interfere with using at least one other shield.) What other conveniences would you put on this type of shield? Breadboard? Jumpers?

Thanks in advance.

MezzoMill: Which AO pin would you use and why? (I would like this shield to not interfere with using at least one other shield.) What other conveniences would you put on this type of shield? Breadboard? Jumpers?

Seems to me that [u]your[/u] actual requirements are the only ones that matter since the shield is for you alone. You're the only one who can define which pins need to be kept free for use by your other shield.

Hey Peter,

Actually, I want this to be a shield to produce and release to others. I was perhaps being too aloof. Basically I want to connect a single analog output from an Arduino into an ARM chip (like a STM32discovery board). However all that I want to communicate between the two chips is a single analog line. Sort of a exercise in minimalism.

I wanted to allow the Arduino to do some preprocessing, using the amazing ecosystem that exists for the arduino, and then have it trigger the arm to do some other processing.

I have used Arduino for a while. However the ecosystem is so vast that I cannot wrap my brain around developing a shield for "any" arduino version. Also there are so many shields that I didn't know what Analog output pin was the least likely to be used.

That is all I was trying to understand. Does that make sense?

MezzoMill: Actually, I want this to be a shield to produce and release to others.

In that case who is your target market, and what do they need your product for?

By the way - the Arduinos do not have any analog outputs.

Mark

PeterH:
I am not sure about the market yet. I will have to figure that out. I just wanted to have something that was dirt simple that allowed signaling from one generic arduino to another ARM based device via my shield. Mainly I wanted to make it stupidly easy so that anyone could use it. While the business feasibility of this is interesting, what I am really curious about is the appropriate way to make the hardware possible given all of the arduino hardware changes over the years.

Mark:
Cant you use the PWM as an effective analog output?
That simply brings up more questions. Has arduino made sure to make the same pins always have PWM across arduino versions?

I am really surprised that my questions are this difficult. I was trying to constrain the problem to make it as easy as possible and yet my questions remain unanswered.

Lets say I want to use Digital Pin 9 (a PWM pin on the Duemilanove) Are veteran arduino users going to scream at me because surely I should have known that shield XYZ uses that pin and tons of people use that shield. Which AO (PWM) pins are essentially off limits?

The shield contains tons of pcb real estate. I was wondering what is the most efficient use of that space. Some people simply build in breakout boards. However I was assuming that this would be geared towards people that don't really want to do more software work and less hardware work. What are some cleaver ideas on using that space?

Unless you know what the shield is for, and hence what environment people are likely to want to use it in, I don't see how any meaningful answer is possible. Make it do what you want. If other people have a need to do something similar, perhaps they'll find you. Unless you have some idea who they may be and what they might need your product for, speculating about what requirements they might have is pointless.

I would like an analog output shield that is I2C that supports e.g. two DAC6573 4 channel DAC’s which have different addresses of course.
That would give me 8 output channels, should be enough and uses only 2 pins.

Would be neat if there was also a 12bit or higher ADC chip - at least 2 channels, better 4

would really make an analog shield complete…