3 x 7 segment display - output speed from radar gun

[matteovinci]

Ok, so i'm a little rusty but wanting to help a friend with a little project

He has purchased a radar gun & is looking to output the speed to 3 x 7 segment displays

currently it outputs ascii data:

<D> [SSS] <CR>

<D> is direction
[SSS] is the speed numeric value
<cr> at the end completing the data packet

though this can aparently be changed to other data types, hopefully hex at the very least

i know the max 6954 aparently takes ascii, though not for 7 segment displays, seems only hex still for 7 segments?

so obviously looking for a circuit that will read the output & drive the 3 displays
the less components the better

have found a few examples but would appreciate some feedback here first

 

[superfrog]

if as I suspect, ascii means ascii coded data over rs232 serial, then I suspect you could find a microcontroller that supports rs232, substract '0' to to your figures comming in, converting them effectively to BCD, and use the precious data to drive 3 7 segments displays. Make that 2 pins for serial in, 2 pins for serial out if needed, 7+3 pins for the display. That should leave you a couple of pins for flashing leds, triggering buzzers, drinving lcds over Mr RB. 1 wire interface or anything else you fancy.

You will need a signal level converter for RS232, a mcu and 3 7 segments displays + 7 resistor + power supply .
I suspect you might even be able to steal power from the serial port, which provides a nice stable high when idling. I am not sure it would be quite enough to drive the seven segment display though.

 

[Sceadwian]

Yeah a small micro controller could drive an actual display driver chip, that'll make it about as simple as you can get.

 

[matteovinci]

now we have the radar output working in hex:

8n1 HEX [2][84][1][SPEED][1][AA][3]

028401 00 01AA03 - No speed Data
028401 6E 01AA03 - Speed Data 110km/h
028401 38 01AA03 - Speed Data 56km/h

(Spaces included for readability)

So the decision now comes as to what will be the best/easiest way to implement this while not having too big of a learning curve

the following was suggested from itsdisplays:

1. MCA2X16 - LED Controller
2. CB232 - Interface board
3. DRA1 - Driver board
4. Some DC power supply 8V - 24 V
5. Custom program

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any suggestions on both the hardware & software side?