CHASING DATASHEET: ELAN OM50 from Woolies corded optical mouse - Page 1
Forum section: electronics / projects

author: gcgrant
author_rank: Contributor
timestamp: April 12, 2017, 10:44:19 am
content: Hi I am trying to hack an optical sensor to get delta x and delta y movement tracking of an autonomous machine I am building. I have bought a cheap $6 optical mouse from Woolies (Woolworths- a supermarket in Australia) and wanted to try and hack this, as I had previous tried with a Agavo ADNS2080 optical sensor, however it operates on 3.3V logic and my MCU is at 5V. Of course I could use a level shifter, but to keep things simple I would rather just find a cheap and easy 5V optical sensor that will give me delta x and delta y.I have managed to find the datasheets on a Taiwanese supplier website for the OM01 and OM02, but these are 16 leg DIP packages whereas the OM50 is 8 leg DIP so interfacing would be rather different.If anybody can point me in the direction of the datasheet for the Elan OM50 optical sensor that would be great, alternatively, if someone could point me in the direction of another mouse to hack under $10 that has a easy to interface 5V logic, that would be good.

author: wraper
author_rank: Unknown
timestamp: April 12, 2017, 10:57:16 am
content: As I guess this is a USB mouse. What makes you think it's 5V logic, is there any controller IC besides this sensor? I really doubt about it. Most likely it only has 3.3V USB interface (with 5V power). On top of that, you would need to build in USB host into your device.

author: gcgrant
author_rank: Contributor
timestamp: April 12, 2017, 11:06:55 am
content: Quote from: wraper on April 12, 2017, 10:57:16 amYes it could be 3.3V logic, (I will measure it, probably should have done before...), however the OM01 and OM02 are 5V and a number of the Avago ones are as well. No there is not another chip on the board.Quote from: wraper on April 12, 2017, 10:57:16 amDepending on the interfacing specs I may be able to access the registers for Delta X and Delta Y without using USB. For example the ADNS2080 uses two wire SPI to do this.

author: wraper
author_rank: Unknown
timestamp: April 12, 2017, 11:22:20 am
content: Quote from: gcgrant on April 12, 2017, 11:06:55 amADNS2080 does not have any interface ready to connect to the PC. Therefore it requires external microcontroller which drives the total cost up and is not financially viable to use in cheap USB mouse.

author: gcgrant
author_rank: Contributor
timestamp: April 12, 2017, 11:43:39 am
content: Quote from: wraper on April 12, 2017, 11:22:20 amThanks for your advice. Do you have the datasheet I was asking for?

author: Buriedcode
author_rank: Super Contributor
timestamp: April 12, 2017, 11:44:28 am
content: That's the trouble with re-purposing parts - you can end up spending more time reverse engineering or searching for info rather than just spend a bit more on a part that will do the job with decent documentation.I am unsure why you are so against 5v. I know you said your MCU is a 5V device, but most MCU's these days are either 3.6V max, or.. 2.7-5.5V and so will happily run at 3.3V albeit perhaps at a lower clock frequency. If you're using an Arduino there are a number of boards - mini/PRO 3.3v, pro mini (native USB) 3.3v, Zero, mega etc.. that can operate on 3.3v. If you're using a PIC then it seems the only PIC's that require a minimum of 4.5V are over 10 years old.Although its a nice idea to hack something already done, sometimes you have to sacrifice some specs for others.

author: amyk
author_rank: Super Contributor
timestamp: April 12, 2017, 11:53:33 am
content: I doubt you'll be able to do anything other than interface it as a USB mouse... for which you already have the pinout.

author: gcgrant
author_rank: Contributor
timestamp: April 12, 2017, 11:59:20 am
content: Quote from: Buriedcode on April 12, 2017, 11:44:28 amI enjoy the hacking as the learning is much better than what you get out of any textbook.Quote from: Buriedcode on April 12, 2017, 11:44:28 amIt's for a uni project due in 5 weeks, not sure I can afford to research chips and start ordering them internationally.Quote from: Buriedcode on April 12, 2017, 11:44:28 amIm using the mega- the output of the pins on the ATmega2560 is 5V, the max input on the ADNS2080 is 3.6V.

author: gcgrant
author_rank: Contributor
timestamp: April 12, 2017, 12:03:02 pm
content: Quote from: amyk on April 12, 2017, 11:53:33 amYou will never never know, if you never never give it a go!

author: wraper
author_rank: Unknown
timestamp: April 12, 2017, 12:52:19 pm
content: Quote from: gcgrant on April 12, 2017, 11:59:20 amLOLBut you have the time to waste on things you'll likely won't ever get working in any reasonable period of time.

author: gcgrant
author_rank: Contributor
timestamp: April 12, 2017, 01:05:40 pm
content: Lol and you're a great help I really appreciate your opinion.

author: wraper
author_rank: Unknown
timestamp: April 12, 2017, 01:19:03 pm
content: I'd say, the only reasonable way buying a new cheap mouse for such purpose, is PS/2 mouse or USB mouse which you know works with passive PS/2 adapter (sensor that can work in both modes), and use PS/2 interface. Anything other, most likely, will be USB only directly to the sensor.

author: amyk
author_rank: Super Contributor
timestamp: April 13, 2017, 02:16:10 am
content: Quote from: gcgrant on April 12, 2017, 12:03:02 pmIt's almost certainly going to be a mask-ROM MCU programmed to act as USB device only. 5 weeks is more than enough time to find a USB host MCU and program it to read data from that.

author: gcgrant
author_rank: Contributor
timestamp: April 17, 2017, 08:25:09 am
content: From the ADNS2080 datasheet:QuoteThis is the kind of chip I want to use. I will probably just hack the one out of the Logitech M220, using a couple of Logic Level Converters made from a 2N7000 and a couple of resistorsQuote from: amyk on April 12, 2017, 11:53:33 amWhere can I get them from in low volume (less than 10), delivered to Australia, this week, without paying exorbitant shipping?

author: jm_araujo
author_rank: Regular Contributor
timestamp: April 17, 2017, 03:53:20 pm
content: You may want to have a look at cheap wireless optical mice. The ones i've opened have an optical IC with a separate Tx module, it's easier to intercept the comms and get the dx dy data between them than the single chip solutions with USB interface. But probably no luck in getting 5V parts.

author: gcgrant
author_rank: Contributor
timestamp: April 18, 2017, 01:26:00 am
content: Quote from: jm_araujo on April 17, 2017, 03:53:20 pmYeah agree, I bought a cheap $8.88 mouse from Officeworks (https://www.officeworks.com.au/shop/officeworks/p/j-burrows-wireless-mouse-black-jbwm697bk) which has a chip (crappy datasheet:http://www.pixart.com/upload/PAW3205DB-TJ3T_DS_S_V1.0_20130514150654.pdf) with 2 wire serial comms, however it seems that it too is 3.3V. All good, couple of logic level converters are more simple to implement than I thought, example circuit shown below:Now I just need to figure out clock speed and serial communication protocols for this chip, as they are not specified in the datasheet.