Sorry for the lack of updates in the past few weeks. The meters are in progress. Two of the big items I’ve been working on are two that had accumulated a lot of technical debt, because they are necessary for release but were not necessary for regulatory compliance or demonstrations.
1. Bootloading and Firmware Protection
Releasing a new product is always a huge risk. No matter how thoroughly one tests, any product above a certain level of complexity is almost guaranteed to have bugs. Most manufacturers avoid that word, preferring the terms “errata” or “known issues”. This is one of the reasons why almost all new consumer products have some mechanism by which to update the firmware.
I can hear some of you thinking “if your multimeter needs a firmware update, you’re doing something wrong”. If this were a normal multimeter I would definitely agree with you. But the Mooshimeter is a connected device that needs to talk to other devices. Even if it were possible to test 100% of all use cases, which it is not, building a connected device in a world of constant updates is hitting a moving target. Apple’s next iOS release could change the permissible Bluetooth Low Energy connection interval to something that messes with the original meter firmware in some unforeseen way, as a contrived example.
For USB devices and computer peripherals, firmware updates are relatively easy: just plug the device in to your computer and flash the device with a file you download from the manufacturer’s website. For a wireless device like the Mooshimeter, a firmware update should not require opening up and taking apart the meter, so firmware updates over the air are a necessity. Exposing an interface to wirelessly update firmware is always dangerous from a security standpoint, because a third party could send malicious firmware which disables the device. But the flexibility and ability to improve the product in the field is worth the risks and extra work.
The electronics all come out of the factory uncalibrated. This means if you hook a meter fresh from the factory to a 5V supply, it will give you a number between 4.95V and 5.05V. Most of the error is constant and intrinsic to the parts, so if you take a few readings of known voltages and currents and store them you can dramatically improve the quality of the readings. To abuse an analogy –
- I have 1000 rulers coming from a factory that should all be 30cm. But in reality they are between 29 and 31cm.
- I have a trusted ruler that I’ve verified with an external authority, and I use it to measure all the rulers coming in from the factory.
- If a nominally 30cm ruler is actually 31cm long, I write that down on the ruler and make a note to multiply all measurements taken by that ruler by 30/31.
Doing this for thousands of meters requires building some hardware to do it automatically. Here’s a picture of that.
3. Doing Anything 1000 Times is Difficult
General rules of thumb I’ve learned about manufacture:
- Doing ~100 of something is easy. It’s exercise.
- Doing ~10,000 of something is easy if you have the money. You can pay a larger operation to tool up and make it happen.
- Doing ~1,000 of something is an uncanny valley where it’s difficult to do yourself and not quite feasible to farm out.
I’ve brought on some extra help to get through some of the tasks.
If you want a slice of life, I used Dropcam’s timelapse feature to cut down 7 hours from an afternoon last week. Woojin is prepping the cases (one of the stretch goals) while I work on the calibration stand and the Golden firmware image.
4. Validating Shipping Addresses
Fulfillment is another big task. It was about 10 months ago that most of our backers pre-ordered a meter, and many people have moved. Expect an email from firstname.lastname@example.org soon to validate your shipping address.
I’m working hard to get your meters out, very sorry for the delays. All the best,