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Need microcontroller help

Drekce

Drekce

Golden Member
Does anyone know of a microcontroller that has a built in D/A convertor, that possibly can scale up to an output of 12 V? If not, has anyone had experience with a specific microcontroller / D/A convertor combination?

I am in charge of the speed control system for a robotic vehicle and will be calculating the needed speed in the controller, and then converting that to an analog signal that will be sent to the motor.

Thanks for any help.
 
I think Microchip has a couple new chips with built in D/A converters (I know for sure they have a/d converters built in). If not, check out the other popular mcu's like intel 8051, motorola, basic stamp.


Why not use a PWM signal instead of an analog voltage? Just feed the pwm through a resistor to a transistor and use that to drive the motor.

what is this for? class, work? what class?
 
Please direct your attention to http://www.cygnal.com. They make some of the best 8051uC based mixed-signal chips (you can get some with a DAC and/or ADC on board... plus comparators, etc.). Parts and development kits can be ordered directly from them, or from Digikey.

EDIT: right now all their parts are 5V tolerant. In the future, they may have some High-Voltage tolerant parts. Check out the C8051F300 if you want an 11-pin 3x3mm MLP package... has an 500kS/sec 8-bit A/D on board. If you need more bits on the A/D or if you need a DAC, check out the F005 or F02x line.

EDIT2: you can always get an external level shifter to go from 12V to 5V.
 
I just found out that my microcontroller will be interfacing with another controller that actually gets the juice from the battery to power the motor. All I need is a low voltage (~5v) input to this controller to tell it how fast I want to go.

We are problobly using a microcontroller from Microchip (they said that they would donate anything we need), they supposedly have a good C like language to go along with their assembly. That is a plus because we need this vehicle done by July.

BTW, this is for a robotics class I am in at school, we are building from the ground up a vehicle that will compete in a competition in July.
 


<< I just found out that my microcontroller will be interfacing with another controller that actually gets the juice from the battery to power the motor. All I need is a low voltage (~5v) input to this controller to tell it how fast I want to go. We are problobly using a microcontroller from Microchip (they said that they would donate anything we need), they supposedly have a good C like language to go along with their assembly. That is a plus because we need this vehicle done by July. BTW, this is for a robotics class I am in at school, we are building from the ground up a vehicle that will compete in a competition in July. >>



The Cygnal parts can be program with 'C' also. The development kits come with a C and Assy. compiler that let's you download code the chip. Cygnal parts also have in circuit debug, JTAG interfacing, on board UARTs, etc. At least check them out.
 
Many of the C compilers for microchip's microcontroller take up a lot of overhead room, which leaves you very little to do complex controls on the chip itself. I tried the PIC C compiler and found that I didn't like it because it took up a lot of space and I did not know what was happening in the microcontroller itself. I would recommend just learning the instruction set for microchip since it is only around 35 instructions you need to learn. That'll let you write extremely efficient, fast, and small programs without all that overhead that many C compilers add.

From what I understand, you are saying that you need to output a voltage between 0-5V to another controller, with 0V being stop, and 5V being max... The thing about adding an external D/A is that you will need a CONSTANT current source or voltage source to reference the D/A, otherwise you will get a very noisy output even when the input is constant and that can wreak havoc this particular application.
 
From what I understand, you are saying that you need to output a voltage between 0-5V to another controller, with 0V being stop, and 5V being max... The thing about adding an external D/A is that you will need a CONSTANT current source or voltage source to reference the D/A, otherwise you will get a very noisy output even when the input is constant and that can wreak havoc this particular application.

To be honest, I am working on this project with an Electrical Engineer (I am a Computer Engineer), so he will be more the one dealing with the D/A and all that stuff. I am gonna be mostly programming, but I needed to choose what controller to use. I will problobly use the assembly language to write the code (I was looking at a Motorola MC68HC11 because I have assembly experience with it, but Microchip is offering us all of the parts for free). If any of you guys are interested I will post here every so often with updates about the vehicle so let me know.
 
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