Create our own tracker for $1!

[biemster]

While it's fun to search the online mall for cheap bluetooth trackers, wait for a month for them to arrive and hope that they contain a flashable chip, let's instead make our own!

The target is very tight: $1 in quantity 100+

I've found a couple candidates already, but definitely would love to see some more suggestions in the comments.

Ideas so far:

1. InPlay NanoBeacon IN100 as suggested by @Cyl0nius in Tracker running on single 1.5V coin battery #26
   https://inplay-tech.com/in100
2. AK1595 beacon tx only IC
   https://www.akm.com/us/en/products/bluetooth-low-energy-beacon/
3. Holtec Beacon transmitter BC7161 (likely needs a support mcu)
   by far the cheapest (~$0.2) if we can figure out how to omit the support mcu
   also might be difficult to source
   https://www.holtek.com/page/vg/BC7161
4. WCH CH592 / 582, CH32V208 or similar
   These are very cost effective (~0.5) and already have a findmy firmware here
   https://oshwlab.com/biemster/ch592tag
   !! ch570 is supposed to be only $0.1 !!
5. Telink tlsr825x
   Have very good support by @atc1441 and @pvvx for example
   but seem difficult to source
6. Ci24R1 + CH32v003
   Another broadcast only chip + mcu, readily available on LCSC

In conclusion I think the CH592 is the prime candidate due to it's availability at jlcpcb for example, and low price and passives count. However I would really like to experiment with the TX only AK1595 and BC7161 for example, since they would do only the bare minimum.

Any ideas or suggestions are definitely very welcome, as are suggestions for a good fab house since this will be my first such project!

[atc1441]

https://www.lcsc.com/product-detail/Microcontrollers-MCU-MPU-SOC_JieLi-Tech-AC6329C4_C5440081.html

[biemster]

https://www.lcsc.com/product-detail/Microcontrollers-MCU-MPU-SOC_JieLi-Tech-AC6329C4_C5440081.html

That one looks awesome, $0.35 even quantity 1! Have you ever programmed one of those?

[atc1441]

Its flashable, but its has a very bad deep sleep :( So not good for a tracker

[biemster]

aww that's a pity, I could not find that in the datasheet indeed

[pvvx]

Cheap keys on ST17H66B are fully mastered (https://pvvx.github.io/iSearching/)
The THB2 project uses SDK for GCC, modified by me and froloffw7, does not contain blobs. Has all sources in C for assembly. Full reverse engineering has been done.
The "KEY2" firmware contains an example of a ready-made BLE button for working in Home Assistant using the BTHome protocol.

BLE OTA is supported in PHY62x2BTHome.html.

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Dependence of average consumption of a device of type "KEY2" on the BLE advertising interval:

Vcc 3.0V. RF TX Power up +0 dBm (10..13+ mA).

"KEY2" Power:
Sleep + RTC: 1.67 uA at 3.0V
Deep-Sleep + KEY (GPIO Int): 0.48 uA at 3.0V
Sleep + RAM + RTC + KEY (GPIO Int) - 3.1..3.3 uA at 1.8..3.3V
Active cycle of work with transmission of BLE advertising with BTHome data - 5 ms, average 7.2 mA (peak up to 18 mA).

Using Deep-sleep is inconvenient - loading the code and initialization takes up to 100 ms with an average current of 7.15 mA.
Similar to normal operation in sleep+RAM mode, average consumption will be obtained when operating in deep sleep mode with a BLE transmission period of 240 seconds.

[atc1441]

Also while 1,50$ and not 1$ this is quite unbeatable in a DIY solution, cheap plug of my FindMy Video :D
https://youtu.be/RPGuPyxdHVw

[biemster]

The ST17H66B is what started this project a couple years ago indeed :) Do you know any online pcb factories that still have them @pvvx ?

[pvvx]

https://aliexpress.ru/item/1005004397030802.html

$1

And similar...
There are more than 5 types of cases on Aliexpress.
The one in the picture is the cheapest.

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Support for ST17H66B/PHY62xx operation in "LE Long Range" mode (this is BLE at a range of 500+ meters) has not yet been published in my SDK, but it has been implemented and tested for a long time. If I have time, I will publish such options as well.
I'm not very interested in Zigbee. Zigbee has too short a range compared to "LE Long Range" and high power consumption.

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https://aliexpress.com/wholesale?SearchText=ST17H66

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The cheapest chips that can be ordered in our country from official suppliers are chips from WCH.
There is no need to publish projects - all SDK variants from WCH are available in the public domain.
Some WCH chips have been used in my production for a long time (in industrial production). But these are not public projects.
(In industrial production, the price of electronic components is the last thing to be considered. There, other criteria are more important, which are far from being used for household purposes...)

[pvvx]

The cheapest CH582M.
Broadcaster is the default test case from the WCH SDK. (Tested in 2022)
Broadcaster - BLE advertising only, no ability to connect or respond to scanning.

RF TX 0 dbm. In the example from the SDK changed: HAL_SLEEP=1, DEBUG - disabled, #define DEFAULT_ADVERTISING_INTERVAL 4800 (3 sec), DC-DC enabled.

On TSLR825x with similar parameters (3 sec, 0 dB) the average current is less than 5 µA, sleep is less than 1.8 µA (32 KB RAM is constantly active), the maximum peak during transmission is about 7 mA.

[pvvx]

It is worth remembering that for beacons like iSearching and similar, the BLE advertising period should be 1 second. But there is not a single SoC that can last 1 year on CR2032 in this mode.
With pulse consumption (pulses up to 8 mA), the capacity of the average CR2032 is only up to 100 mAh. CR2032 batteries costing more than the key fob itself have a slightly higher capacity.

CR2450 will work more than 2 years, only due to lower internal resistance (lower voltage drop under 8 mA load).

As a result, the price of the chip is completely unimportant if CRxxxx batteries are used. It will cost less than the price of the battery.
Cheap alternative only 2xAAA.

Another solution is to install a large capacitor in the power supply chain (more than 100 uf). But for a capacitor with a large capacity and low leakage, the price is already equal to or higher than the SoC price :)

The target is very tight: $1 in quantity 100+

When shipped with battery and 1 year of operating time = Impossible goal at the current technological stage of manufacturing cheap SoCs (if you are not in China) :)

[pvvx]

https://www.lcsc.com/product-detail/RF-Transceiver-ICs_PHYPLUS-PHY6222AAQC_C2836482.html

Qty.	Unit Price	Ext. Price
1+	$ 1.7501	$ 1.75
200+	$ 0.6788	$ 135.76
500+	$ 0.6538	$ 326.90
1000+	$ 0.6428	$ 642.80

:) :) :)

THB2, BTH01 - They can be less than $1.5 each on Aliexpress.

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In WCH SDK, working with "LE Long Range", "PAwR" (new Bluetooth standards v5.4) is only available for CH32V208.
"LE Long Range", "PAwR" and standard encryption of BLE advertising in BT5.4 completely kills Zigbee.

Previously, several WCH LinkW (CH32V208) were purchased on AliExpress for $1.5, including shipping.

[pvvx]

TLSR827x Find My Network Accessories SDK Developer Handbook

[pvvx]

pvvx/THB2#94