FE33L serial output to RS-232

[Mark McGee]

Hi

Does anybody have experience of the Maplin (FE33L) temperature control
module?

It has a 13-bit serial output (it's a custom BCD type of thing). I'd
like to convert this 13-bit data in to RS-232 that I can plug in to a
PC serial port and poll with software.

the module has a data pin (0v-1.5v) and a dataclock(0v-1.5v) which
pulses on for 0.125 ms, and holds for 1ms for each of the 13-bits.

I assume I'll need to connect this to some kind of shift register
(16-bit), but I'm not sure if I can then throw this 16-bit register as
some IC which'll send it via RS-232 for me.

Any ideas?
Regards,
Mark

 

[petrus bitbyter]

"Mark McGee" <mark.mcgee@csfb.com> schreef in bericht
news:b9ca7c6f.0409300745.44b643e9@posting.google.com...

Hi

Does anybody have experience of the Maplin (FE33L) temperature control
module?

It has a 13-bit serial output (it's a custom BCD type of thing). I'd
like to convert this 13-bit data in to RS-232 that I can plug in to a
PC serial port and poll with software.

the module has a data pin (0v-1.5v) and a dataclock(0v-1.5v) which
pulses on for 0.125 ms, and holds for 1ms for each of the 13-bits.

I assume I'll need to connect this to some kind of shift register
(16-bit), but I'm not sure if I can then throw this 16-bit register as
some IC which'll send it via RS-232 for me.

Any ideas?
Regards,
Mark

An RS232 PC COM port accepts datawords up to eight bits. So you have to read
out the MAPLIN module, split up the data and then feed it to the PC. I'm
sure it *can* be done using logic building blocks but you will end up with a
pretty large and expensive board full of electronics. The way to do this
type of conversion is using a microcontroller these days. You will need two
transistors to amplify the 1.5V pulse to 5V. The micro for the protocol
conversion and a MAX232 or similar to convert the 5V output pulses of the
micro to the RS232 levels required. As for the micro you have a lot of
choices. If you want a quick and easy result, take one with a build in UART.
If you have to make hundreds or more, take the cheapest micro you can find.
The programming is the hardest thing of course but make no mistake, building
the same thing in nonprogrammable logic reliably is much harder.

petrus bitbyter


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[mark.mcgee@csfb.com]

Thanks for the advice. I found this resource www.piclist.com and
there's sample code for RS232.

I only have to make 1 or two of them, and maplin suppy the PIC 16F628
for Ł2.99

Regards,
Mark