Yet Another IoT Communication Standard: NR+

Iot standard xkcd

There is an old xkcd comic I like to refer to when people talk to me about industry standards. Everyone seems to be on a separate bandwagon and eventually, some trigger point occurs in that domain and one standard will win out based on market forces. It may not be the greatest standard but it’s the one which is the most popular. This week I got introduced to a new communication standard called the DECT NR+(New Radio+) which is based on DECT-2020 released as part of 5G. It has a few interesting things going for it to spike my interest. Let me explain.

It’s a non-cellular standard(unlike NB-IoT and LTE-M), meaning you don’t need it to talk to mobile towers(So no need for subscription charges, similar to BLE, LoRa). There are no licensing headaches and charges, as it’s on an unlicensed spectrum range of 1.9GHz which is free to operate worldwide(Except India and China). Its meant to cater to Ultra-Reliable Low Latency Communication (URLLC) market with a latency spec of 1ms which is pretty great. Reliability is the key term here, they want this standard to be a replacement for a wired system. Ask any engineer they would still prefer wired solutions like ethernet for mission-critical data communication. NR+ is supposed to be the wireless equivalent of that.

NR+ can do high data rates of communication (Think WiFi) which will ensure that high bandwidth use cases are taken care of. Caters to massive Machine Type Communication (mMTC) type of use cases like self-driving cars on the road, low-power sensor networks, and smart meters. It can support upto a 1mn nodes in 1sq km, which is also huge. It has a large range claiming to be at around 1-2km on open fields. Has a self-healing mesh in which if one node fails in the network, data can be rerouted through some other node to reach its destination.

Well for internet connectivity for NR+ mesh, you would still need an edge device communicating to the internet. This standard is still in the early stages and will potentially hit commercial products in the next couple of years. There seems to lot of good stuff going for this standard, but will it win out? Only time will tell. If you need to learn more about this I would suggest reading the ETSI standard ETSI TS 103 636-1 for the full specs and checking out a webinar from NordicSemi on this for an overview of the tech. NordicSemi seems to be heavily invested in this as the next big thing.

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Boat Rocker Headphone Teardown and Fault Diagnosis

Boat Headphone Teardown
Boat Headphone Teardown
Boat Headphone Teardown
Boat Headphone Teardown

A friend of mine dropped off a pretty old pair of wireless Bluetooth Boat Rocker headphones which were not working. The power LED turns ON but it’s unresponsive after that. Opened it up and first did a charge test with a USB current meter and found that there was no current taken from the power supply. That’s usually bad news, as that could potentially mean that the battery is bust or the main chip is blown. I opened up the battery compartment and there was no bulging of the battery. The battery was showing voltage, which was slightly low, but nothing too concerning. Then I desoldered the battery and connected a spare battery right on the PCB. Then plugged in the USB meter and voila the new battery is charging. Turned out the culprit was a faulty positive battery wire running all along the headband. It had no continuity and it was broken in between. Replacing that thin wire should get the headphones backup. The device wasn’t turning ON as the main chip couldn’t detect the battery due to the broken wire, even though it was getting external power.

Coming to the circuit analysis, these BLE headphones contain a Bluetooth chip from the Taiwanese manufacturer Airoha (AB1510). It’s a DSP chip with 48MIPS. It has all the bells and whistles for audio input, processing and outputs. It has a BLE PCB antenna. The great part of this chip is a built-in battery charge controller capable of charging at 400mA with protection. This eliminates the need for an external charging circuitry altogether. I couldn’t find a pricing for these chips though. If anyone knows please do comment. The other main IC is 24C128A, which is a 2-wire Serial EEPROM from Microchip to mostly store audio presets I suppose. The LiPo battery has a capacity of 450mAh. All in all, a reasonably well-designed headphone.

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