Two-axis optical encoder without special code strips
Adobe Portable Document Format - 36.50 kB - 11/23/2016 at 11:31
Gerber files v1.0
Zip Archive - 14.43 kB - 11/23/2016 at 11:31
Just a quick update:
I finally got a reply from our distributor. At the price they quoted us, we should be able to sell breakout boards with module for about USD 15/each + shipping. The initial run would be at quantity 200.
Currently, the main issue is the substantial lead time of 12-14 weeks. There is probably no way around this.
So now, I'll have to decide which way to continue with this project:
There is also the option of having everything sent to us and then forwarding the single devices ourselves. However, this would only make the boards a lot more expensive due to shipping, etc.
If you have any recommendations, please let me know.
I wrote a very basic Arduino library for the sensor. It is still missing some parts (e.g. the I2C address), but should be a good starting point. It's available on github: https://github.com/aesora/aesora_PMT9123
At least up to this point, it's a clean room design and only based on information that's publicly available.
The breakout board is done. The newest release can be found at https://github.com/aesora/PMT9123_breakout/releases/latest. It has few different components and combines the example schematic from the datasheet with a LDO and a simple level converter. This way it can be used with both 3.3V and 5V logic. All pins on P1 are documented on the bottom.
While reading through Hackaday (http://hackaday.com/2016/11/21/diy-optical-sensor-breakout-board-makes-diy-optical-mouse/), I noticed that there is some interest in optical tracking sensors. The most common type are the ones found in optical mice. While those sensors can be useful as optical encoders, there are better options. Pixart, leading manufacturer of mouse sensors, recently added some sensors for optical tracking to their line up. One of these is called PMT9123. It can be used as optical encoder with 2000cpi (0.0127mm resolution) in two axes at speeds up to 25ips (635mm/s) and accelerations of up to 8g. Those values should be sufficient for most 3D printers. Data is output using I2C.
The main issues with this chip are:
Since I am currently working with Pixart on a different project, I believe that only the first one is an actual issue. The second one depends on how many of you are interested in this sensor. So let me know here and if there is enough interest, I will get pricing information and start group get.
If you don't have a Hackaday.io account, just leave a comment here: http://hackaday.com/2016/11/21/diy-optical-sensor-breakout-board-makes-diy-optical-mouse/#comment-3282813