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emulating rs232 bi-directional device.

Former Member

These questions are following on from my previous question about monitoring rs232 traffic. I had some good success and now have some questions about the general approach to take to rebuild teh device using arduino.

Over the past week I have been mapping out the controls of a rather ancient rs232 remote control for a piece of audio equipment. using port monitoring software etc I now know what each control sends in terms of messages etc.

The device has 6 faders, 24 buttons and can display 48 ASCII Characters split into 1 lcd of 2x12 chars and the other 1x24 chars. The remote also has a stereo db level indicator made up of 2 rows of 16 leds.

so far I have come up with this..

PROBLEM 1 The 6x faders are easy enough without even needing a mux (I think, at least on the ProMini) these vales can be read in, mapped from 0 -255 and the output of each would need to be converted to HEX and have the corresponding control byte prepended to it's value before being spat out on the serial bus.

PROBLEM 2 The 24 buttons I think will be somewhat more of a challenge, I'm wondering if there are keypad or scanning options I could try for this as there are not 24 inputs available..

PROBLEM3 As I mentioned above, there are 2 screens in the device, a 2x12 at the top and a 1x24 at the bottom. I believe these screens are chained in some way because If i send more than 24 characters to the 1st display they will overspill onto the bottom (1x24) display

The commands come over the rs 232 bus like this each message of text begins with <00> and ends in <03> so a full 24 character message would look as follows 00 74 68 69 73 20 69 73 20 61 20 74 77 65 6e 74 79 66 6f 75 72 63 68 61 72 03

but if this message were longer, how would I want to think about spilling over onto the next screen?

I guess these are 3 large questions that maybe I should split up. I just wanted to get this all out in context.

thanks, and look forward to hearing opinions. BradT

  • 0

    Brad,

              As you note problem 1 can be solved fairly easily in the manner you describe, I believe the 'write' command as opposed to 'Print' will output the characters in Hex format (Binary).

    Problem 2.  MAJENKO. com make an SPI add on board that provides an extra 32 I/O, this will give you 24 inputs.  I use these to drive 24 opto coupled relays.

    Problem 3. A 4*20 LCD can display 80 characters, If you use an I2C backpack on the LCD you can get the 32 I/O and LCD on only 5 Arduino pins!   Alternatively if you want two LCD displays you can set the address of the two I2C displays to different values and therefore send whatever characters you want to each display.  This would use 7 Arduino pins.  There are Arduino libraries for all these devices.  If you need more information on anything please ask.

  • 0 in reply to bobcroft

    thanks bob,

    I'm going to be more specific and ask individual questions about the problems I need to get over. thanks.