Re: 8051-class "learner" board - is it worth making one?

[Jeff Shirley <spamzilla@xxxxxxxxxxxxxx>]

In comp.robotics.misc zwsdotcom@xxxxxxxxx wrote:
> This is a crosspost from comp.arch.embedded, with some enhancement.

> The story:
> I semi-accidentally acquired a fairly large quantity of surplus ROMless
> 8051-class parts in DIP-40 packages. These include Intel and Signetics
> 8031, 8032, and lots of Dallas DS80C310 and DS80C320. Along with them
> came a bunch of 6264 and 62256 SRAMs.

> Somewhere in my archives I have a layout for a board that takes a
> DIP-40 8031 and has 32K of program flash and either 2K, 8K or 32K of
> RAM. It also has a level-shifted serial port, and some miscellaneous
> headers for GPIOs and such.

> In this day and age, is it worth my while to do a production run of
> these boards and offer them for sale to get rid of the surplus chips? I
> would write a small bootloader and preload that into flash so you
> wouldn't need additional hardware to load code onto the board.

> I figure I could [afford to] sell an assembled board for ~USD35.

> When I posted the above in c.a.e I got some suggestions, including to
> ask the question again here.

> Is that old design of mine even useful as it is, or would I have to
> build something more exotic to make it interesting?

Hi.

I have a shelf full of 8051 boards and chips, which is probably why I am the
only one in my club using 25-year-old technology in a robot.  I wanted a board
with a serial boot loader, where I did not have to re-vector the interrupts
from the boot loader.  I designed a small board that ANDed PSEN and RD, and
used a TTL signal to swap between the boot loader (EPROM) and RAM at location
0x0000.  That way I can load code, toggle the signal, reset and run the code
from RAM.

I did finally find a handful of boards I could modify to work this way, and
used them instead of my own design.  It was also nice that these boards had
a hook for a memory mapped device (8255, quadrature decoder, etc.), and could
support a few different RAM and EPROM sizes.

I am not sure how much of a market there is for "vintage" 8051 boards.  I am
in the process of porting some of my stuff to ARM, and have started to really
appreciate the newer 8051-core offerings from companies like Atmel and Analog
Devices.  The extra peripherals are great, and it is nice not to have to use
I/O ports for external memory.  I might still be a customer if you go ahead
with the project, and your board supports code developed with SDCC.  I would
probably be more inclined to buy bare boards, however, and then probably only
two or three.

Jeff.
--
Jeff Shirley
spamzilla@xxxxxxxxxxxxxx
"Bill Gates is filthy rich, but that doesn't mean I want to be married to him."