Finding A USB Interface on an RS232 Barcode Reader - Page 1
Forum section: electronics / projects

author: dexters_lab
author_rank: Unknown
timestamp: September 14, 2016, 10:14:02 am
content: I pulled this nice self-contained barcode reader from my last teardown, it's a CINO FM480-02F with an RS232 interface on it.Looking inside there is the optical parts, a custom CPU which looks an ARM processor given it has 'ARM' written on it, some power regulation stuff and a Sipex 3232 RS232 driverFrom the maker it's available in three versions: USB, RS232 or bothi will hazard a guess the only difference is the cable, the programming instructions also don't make any distinction between the interface versions, so thereshouldbe USB somewhere on the internal 15 pin connector so i thought it would be fun to see if i can hack a USB cable to it and give it a try. But it's pretty small and i'm sure i counted 8 layers on the PCBWhat would be the best way to explore those unused pins to find the USB Data lines? What would i be looking for?My RS232 cable has 6 of the 15 lines connected, i have pinned out the GND, +5v lines already

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 14, 2016, 10:27:14 am
content: Are you sure the USB version is not just supplied with a RS232-USB cable?

author: dexters_lab
author_rank: Unknown
timestamp: September 14, 2016, 10:32:02 am
content: Quote from: PA0PBZ on September 14, 2016, 10:27:14 amyea, i am pretty sure it has internal USB and not just some converter, there is a whole load of programming options for the USB HID (Keyboard) built into the reader

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 10:41:39 am
content: Found this...9-pin D-sub female (RS232 version)USB 4-pin Type A (USB version)15-pin D-sub HD female (Universal version)So going by that it will somewhere have USB and RS232 on that connector, as they are using a 15pin DSub.Start analysing the pins not used by the RS232 cable

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 10:44:01 am
content: Now if this in Pin to Pin, you have your answer...Pins 8 + 12 for the USB Data.

author: dexters_lab
author_rank: Unknown
timestamp: September 14, 2016, 01:08:25 pm
content: thanks guysok it doesn't seem to be pin-pini've set the reader to USB HID mode, now without this being plugged in to the USB host am i going to see anything at all? if i do what's it going to look like on my scope?scoping around i did find a burst of data on pins 13 & 14, which have two test points just at the connector (see attached pic), these also run to the 6V8UOCH device just to the left, '6V8U' comes back as a ESD protection device for USB so thought they might be the DATA +/ -.I did connect them up to the data pins on a USB cable but got no response when i plugged it to a pc

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 01:14:43 pm
content: Quote from: dexters_lab on September 14, 2016, 01:08:25 pmDid you have the Ground and +5V from the PC as well, rather than from a PSU, as I've had devices that need all 4 wires. Even if it already had power elsewhere. Also did you try reversing the data +/-.You can deffo rule out what pins are not the right ones by tracing the 9 Pin Dsub back to the connector, which leaves you 6 possible pins left.No idea with analysing USB data signals when not connected to a host, I'm sure someone will chime in with that side of things though.

author: rrinker
author_rank: Super Contributor
timestamp: September 14, 2016, 06:42:12 pm
content: What are those 4 pads in a row plus 2 set further back in next to the pushbutton? That layout looks suspiciously like a PC mount USB socket.

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 07:25:02 pm
content: Quote from: rrinker on September 14, 2016, 06:42:12 pmThat's the connections to the other PCB that goes through the board vertically.The 4 in a row are SMT components.

author: dexters_lab
author_rank: Unknown
timestamp: September 15, 2016, 11:02:52 am
content: thanks for the help guysi played a little longer with it to no success, obviously it's not worth spending time on given how cheap USB barcode scanners cost so i'm not going any further with it.