wireless rs232 help - Page 1
Forum section: electronics / projects

author: cpposteve
author_rank: Regular Contributor
timestamp: May 02, 2016, 11:47:37 am
content: hi all. first post here so hoping someone can help :-)im after making some kind of wirefree rs232 device.i have a programable ecu in a car im building which uses the old db9 connectors. Id like to make the programining wirefree due tothe ecus location and for the fact that lets face it wireless is just so much nicer to work with. no cables to rip out etc.Iv done a little research and found the hc-06 and wondering if this can be usedor is the outputing data just usb data?as i cant seem to work out how you would get the DTR/DSR/RTS/CTS pins to work?or do you not need these pins (optional)hope this kind of makes sense and sorry for my lack of knoledge but hope this forum will help me with this soon ;-)steve

author: ChristofferB
author_rank: Frequent Contributor
timestamp: May 02, 2016, 02:29:36 pm
content: The handshaking (DTR/DSR/RTS/CTS) can be omitted in some occasions, connecting DTR to DSR and RTS to CTS, thus making the device think it's "always allowed" to transmit/receive - I'd test that out with a DIY RS232 cable realizing that first.Remember to do it on both connectors.Have never heard of the wireless module, though.

author: Neverther
author_rank: Regular Contributor
timestamp: May 02, 2016, 02:33:47 pm
content: I use HC-05 as I need master mode. Just replacement for odometer with fuel-usage/etc. It is inside the intrument cluster and it communicates to bluetooth slave on the ECU diagnostics line (pre OBDII).As it is inside the cluster, I just got a menu item to restart the unit in slave mode.Once in slave mode the unit waits for serial communication and once it sees something it triggers the watchdog reset.It is running atmega328 so I have bootloader there.So one I start uploading with avrdude it triggers the reset, reboots into bootloader with bluetooth still connected reprograms the unit.No modifications needed for avrdude, I tought about adding a start reset command via serial but as avrdude works straight I left it out.Basically you could just interface the HC-06 to something with serial line, then use another serial line (HW or software) to retransmit. Just when it first time detects something on input (or implement reset command) you emulate the pin states on DTR/DSR/RTS/CTS to reset/initiate reprogramming.HC-06 just handles the RX/TX so other commands to the serial interface dont do much.

author: cpposteve
author_rank: Regular Contributor
timestamp: May 02, 2016, 05:16:34 pm
content: thanks all. will give it ago linking the two out and see how it goes. just out of interest though is the tx and rx on the hc-06 the same type of signal as what the standard rs232 tx and rx uses??steve

author: Neverther
author_rank: Regular Contributor
timestamp: May 02, 2016, 07:29:12 pm
content: Level conversion. Old max232 (which will work quite far as it will level convert cts and rts too if you implement them) or just couple transistors with basics will do the job.Google will tell.

author: cpposteve
author_rank: Regular Contributor
timestamp: May 02, 2016, 08:28:15 pm
content: So I could go like this...Ecu via rs232 -- max232 -- hc-06 -- Bluetooth to laptop? Would that ok.

author: helius
author_rank: Super Contributor
timestamp: May 02, 2016, 08:36:59 pm
content: Check the offerings ofhttp://www.lm-technologies.com