Since March this year, orders of OpenSprinkler have been increasing rapidly. Within a couple of weeks, we’ve done two batches of OpenSprinkler 2.3 at our local manufacturer — Worthington Assembly Inc. (WAi). Previously I have blogged about OSPi manufactured at WAi, and I’ve shown videos of their SMT surface mount manufacturing pipeline, including pick and place machine and reflow oven. This time, I was able to get two great videos of the selective soldering machine, which is used for through-hole soldering. Check the video here:

Below are some snapshots. First, before soldering, the boards are queued, and all through-hole components are hand inserted to the board,

Next, each board goes through a pre-heating machine to get pre-heated, and then sent to the selective soldering machine. The selective soldering includes a fluxing phase, and soldering phase. Check the video above for details.

This is the result of the selective soldering. Looks very nice, and much better than hand soldering!

I realize that I haven’t properly announced OpenSprinkler 2.3. So let me give a brief introduction here. OpenSprinkler 2.3 was released ahead of schedule, due to a weird supply chain shortage issue. Basically, OpenSprinkler 2.2 was using Atmel’s ATmega644 microcontroller. A few months ago, as we were about to purchase another batch of 2.2, it suddenly occurred to me that there was a shortage of ATmega644 — our Chinese suppliers said they couldn’t source this component. Then on the US supplier websites, ATmega644 ends up costing slightly more than its next upgrade ATmega1284, which has twice the flash memory size and four times the RAM size! This is very surprising. Even today, you can see that the price of ATmega644 is no less than ATmega1284. Because of this, it no longer makes sense to stick with ATmega644, therefore we decided to immediately upgrade to OpenSprinkler 2.3, by using ATmega1284. This is pretty much the only major change between 2.3 and 2.2. Some other changes include using as much SMT components as possible, to reduce the number of through-hole components.

At the moment, the firmwares for OpenSprinkler 2.3 and 2.2 are pretty much the same. However, since OpenSprinkler 2.3 has doubled the flash memory size and quadrupled RAM size, it’s geared up for major firmware upgrades in the future. At the minimum it will be able to allow for a larger number of stations, more programs, and more data stored in the microcontroller.

So in sum, this was an upgrade that went ahead of schedule, and was due to an unexpected shortage of the previous microcontroller.