Need Micro Controller Evaluation

[[email protected]]

I am looking for a development board for controlling lab instruments
and doing some experiments. I expect to use simple interfaces to
sensors and to use digital control and also to sometimes interface with
a PC for recording data. Getting up and running quickly is important,
as is having a flexible system.

I spent a year doing professional firmware on an H8 development board
but it was six years ago and I don't remember what I used.

What I think I want is a development board/micro controller with:
A few timers,
A few channels of ADC (speed not too important-so one ADC should
do. I could live with an external multiplexor)
Access to the micro's pins. Either via headers or with some space
for the
Flash memory. 32K should be plenty
A few K of RAM.
An on board LCD display (32 charecters should be over kill and
could live with less). I Could add this but it would be much faster if
the eval board came with one.
C compilier
Debugger
USB port would be nice
Price <$350 for whole system. <$200 would be ideal.

Any advice one who makes good boards and has good documentations would
be greatly appriciated. SHould I stick with an H8? Does it matter?

 

[Jonathan Westhues]

What I think I want is a development board/micro controller with:
A few timers,
A few channels of ADC (speed not too important-so one ADC should
do. I could live with an external multiplexor)
Access to the micro's pins. Either via headers or with some space
for the
Flash memory. 32K should be plenty
A few K of RAM.
An on board LCD display (32 charecters should be over kill and
could live with less). I Could add this but it would be much faster if
the eval board came with one.
C compilier
Debugger
USB port would be nice
Price <$350 for whole system. <$200 would be ideal.

Perhaps one of these would suit you:
http://www.olimex.com/dev/avr-mt128.html (plus a programming dongle)

There is a C compiler: you can use avr-gcc, for free. There is no USB but
there is an RS-232ish serial port. There is a JTAG port and supposedly that
supports debugging; I've never used it. 16x2 LCD, and the micro (ATmega128)
has the ADCs, flash, RAM, and timers that you need. Lots of GPIOs are
brought out to headers. It's certainly cheap.

I don't know anything about H8 processors, other than that I don't know
where to buy them. PIC, AVR, 8051, and (newer) MSP430 processors seem to be
most popular in that range.

Jonathan
http://cq.cx/

 

[John Miles]

Perhaps one of these would suit you:
http://www.olimex.com/dev/avr-mt128.html (plus a programming dongle)

There is a C compiler: you can use avr-gcc, for free. There is no USB but
there is an RS-232ish serial port. There is a JTAG port and supposedly that
supports debugging; I've never used it. 16x2 LCD, and the micro (ATmega128)
has the ADCs, flash, RAM, and timers that you need. Lots of GPIOs are
brought out to headers. It's certainly cheap.

That's pretty cool for $50, all right. But what's with that bizarre RS-
232 level converter with all the bipolars and diodes and stuff? I'd
rather see a MAX232ACPE or something that puts more than 5V into the RxD
line.

-- jm

 

[Jonathan Westhues]

That's pretty cool for $50, all right. But what's with that bizarre RS-
232 level converter with all the bipolars and diodes and stuff? I'd
rather see a MAX232ACPE or something that puts more than 5V into the RxD
line.

1x MAX232 (TI part) 0.5086 CAD
4x 1u Y5V (!) 0603 0.0639 CAD
------
0.5725 CAD


1x MBT3946 0.06135 CAD
2x FDLL4148 0.04908 CAD
5x 0603 resistor 0.04908 CAD
1x 10u 25 V 0.08616 CAD
-------
0.24657 CAD

(Digikey pricing for 1000 units)

Bizarre, maybe, but I don't see how to make it cheaper. You have to receive
the negative voltage before you can transmit it...

Jonathan
http://cq.cx/

 

[John Miles]

Bizarre, maybe, but I don't see how to make it cheaper. You have to receive
the negative voltage before you can transmit it...

That's what I mean. It might have seemed clever, and it might actually
be clever if you can assume your DTE will wiggle its TxD line up and
down every once in awhile, but hey, it only saves 33 cents on a $50
assembly. It seems like one of those clever ideas that always comes
back to haunt you in the end.

Although to be fair, DigiKey wants $5.51 for the MAX232ACPE part I
mentioned! I never noticed what I was paying for those, since I've
never purchased more than a couple at a time. It does let you use
cheaper 0.1 uF ceramics, but sheesh, that's an expensive chip.

-- jm