The return of the camera!

A project log for Controlling a cctv camera with arduino!

A dream school project: control one or more cctv cameras with only a arduino

pixelboPixelbo 03/01/2022 at 19:544 Comments


My vacation is now over, I had a little tchat with my teacher and we figured out that the most "easy" way to have multiple cameras without denuding the already present wires is to have:

-A pair of wires with RS485 bidirectional 

First of all we need to configure the camera via the dip switch, we have 3 possible modes:

(TX is here from Arduino to camera and RX camera to Arduino)

-RS422 with 5 wires (GND, TX-, TX+ and RX- ,RX+)

-RS485 with 4 wires (TX-, TX+ and RX- ,RX+)

-RS485 with 2 wires (TX-, TX+ OR TX-, TX+ and RX- ,RX+)

Of course we want RS485 with 2 wires, however we encountered a problem: the TX module was supplying 5v (in idle state) to the camera even when it responded (For more explanation).

The solution to this problem: control the TX module's idle voltage with pinout!

I use an esp32, so the pins delivers 3v3 but that's not a problem because the chip function fine with 3v3 and the camera still works (The voltage differential is enough big)

So I grabbed my jumper wires and a schematic like this:

You can see that the TX module's Read Enable, Driver EN and vcc is controlled by tht IO33.

This module pins work like this

DE pin
Module state
0VHIGHHIGHResidual voltage

but what is the is the result, here are the result in UART communication from RX module to Arduino:

Still "One problem": we detect also the TX module transmission but that's not a problem because we can filter it out in the software:

Well that was all for today, see you next for Software Improvements!

Bonus: the code is now looking like this (tempory code):

#include "Arduino.h"
#include <Pelco_And_Arduino.h>
/////////////////Address,baud,tx  ,rx , logging

PelcoCam PelcoCam(0x01, 9600, 25, 26, true);

int testpin = 33;

void setup() {
  pinMode(25, OUTPUT);
  pinMode(26, INPUT);

  pinMode(testpin, OUTPUT);
  digitalWrite(testpin, HIGH);
  Serial.println("Init Finished!");

void loop() {
  digitalWrite(testpin, LOW);
  digitalWrite(testpin, HIGH);


jumpjack wrote 03/14/2024 at 19:34 point

Thanks, I did it!

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Pixelbo wrote 03/14/2024 at 20:47 point

Amazing job!

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jumpjack wrote 03/10/2024 at 19:43 point

Any idea about how to simulate your peoject in WOKWI?

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Pixelbo wrote 03/11/2024 at 17:52 point

I think if you can decode the whole message from the arduino and then send back an Acknowledge message back to the arduino it could be done. Messages follow a data frame and shouldn't be too hard to decode.

I could help you on that if you want, however I'm studying and have exams in the next weeks.

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