The Amp Hour Electronics Podcast

Welcome Jared Wolff of Circuit Dojo!

• Jared is a graduate of the Rochester Institute of Technology (which Chris also considered attending). He did co-ops while there, like we talked about on last week’s episode.
• While on co-op at Cisco, he was in the cable group and marveled at the techs doing repairs with magnet wire.
• He is an east coast guy at heart, so he moved back to Connecticut eventually
• Jared worked at Apple for a while, but the lifestyle is difficult because of time requirements and stressful travel. He was also there when Steve Jobs was still around and there was a bit of over the top hero worship.
• Nordic’s early bluetooth chipset was the nRF8001, which was a transceiver over SPI (no micro)
• Working for startups was interesting if you thrive on doing a lot of different things
• Burnt out on his last startup, decided to ride his motorcycle up and down the west coast. He got sick and ended up diagnosing himself with Valley Fever, a fungal infection prevalent in one of the places he visited.
• After healing up, he went to Taiwan for 4-6 monhs.
• There is a semiconductor fabrication program at RIT. There is a silicon ingot in a display case out front there.
• While recovering from burnout, a previous mentor hit him up for the IoT project.
• Mix of international and domestic manufacturing in his past
• A lot of military nearby in CT
• Comparison quotes with Taiwan, it was only a few dollars more for domestic production.
• Currently building a board with an nRF9160 module, the new cellular module from Nordic Semiconductor.
• Current status of nRF9160 is that it is shipping and working on different carriers throughout the world on Cat M1 networks.
• What does it take to get a modem talking to towers?
• Modems abstract commands in software
• Jared will be testing for FCC, ISED, CE
• Working with Resin
• The cellular module is pre-certified but carriers still want you to test your design on their network.
• Verizon requires over the air firmware capabilities, in case something goes wrong. The nRF91 firmware OTA is on the application side, which is unusual.
• Jared is hoping the modem will have bluetooth at somepoint as well. The external wideband antenna he is using might be good enough.
• Crowdfunding had an external antenna included.
• There are different categories of cellular service. Most cellphones operate with Cat 4 or Cat 6 connections. The higher the category, the faster the speed.
• Cat M1 is the slowest on LTE. NB-IOT is different equipment, so it isn’t even considered to be LTE.
• Based on the development from Nordic, Jared is using Zephyr to run his board.
• It’s an Real Time Operating System, but “feels” like linux for embedded. Zephyr is built on top of the chip’s SDK. “West” is the downloader that pulls in necessary dependencies, based upon a definition file.
• Huge library of boards available
• Jared wrote a post on how to create your own drivers on Zephyr
• The Device tree maintains swappability
• The nRF91 board is based on the adafruit feather form factor. Jared had previously created the air quality wing, which had various sensors:
  • TVOC
  • Humidity / Temp
  • Particulate sensor
• Compatibility matrix on the Nordic site
• Chris recommends checking what kind of coverage you have with open signal.
• Though the first board run is no longer for sale, some boards are available soon. You can get a discount on a board at jaredwolff.com/amphour
• You can also follow along on Jared’s progress on his blog, where he also writes about firmware tests.