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To develop, for use in an tool rental, an electrical tool power-on and utilisation monitor, small enough to be placed into the wall plug. Basis is an Attiny84A, programmed to constantly send its collected data via 2.4 GHz radio nRF24L01+ to a base station.
Power is provided by a capacitive power supply directly off the mains. Power consumption of the connected tool is measured, roughly, via small-scale magnetometer HMC5883L, making it possible to collect and summarise utilisation hours under a certain number of different consumption conditions.
Since flash and eeprom memory only sustain a limited amount of write cycles, and a cyclic writing say every five minutes would lead to 100.000 write operations per year for a constantly connected tool, the collected data is written from SRAM to permanent storage only at power drop using remaining capacitor energy.
Data emitted via radio is collected at a base station, forwarding the data to a specific Internet service which stores the data records into a database and then provides versatile facilities for evaluation, statistics and/or B2B connectivity to a rental tool. The base station thus must support both 2.4GHz radio and an Ethernet connection to the Internet. A speaker would be handy as well. In my case the previously design of an IOT base station is reused for this purpose..
It is important in this context to be able to update the software not only of the IOT base station (see there for solution), but also of the remote power monitor nodes. This implies the design and implementation of a radio bootloader protocol and software for the monitoring nodes, and a respective server software for the IOT base station, which itself would draw the necessarz software from the Internet.
Das Board wird mit Plastik 70 Super o.ä. behandelt und/oder in eine Silikonhülle verbaut. So kann dann eine der zwei Gerätezuleitungen mit einem dünnen Kabelbinder definiert über oder unter dem Magnetometer entlang geführt werden.
Ident | Spez | Größe | Nr | Einzel | Summe | |
Version V05 | ||||||
C1,C2 | 220nF, 450V | 1210 | 2 | 0.384 | 0.768 | |
C3,C4 | 100μF | 1206 | 2 | 0.600 | 1.200 | |
C5 | 1μF | 0402 | 1 | 0.019 | ||
C6,C16 | 100nF | 0402 | 2 | 0.005 | 0.010 | |
C7,C8 | 18pF | 0402 | 2 | 0.064 | 0.128 | |
C9 | 10nF | 0402 | 1 | 0.006 | ||
C10 | 1nF | 0402 | 1 | 0.006 | ||
C11 | 33nF | 0402 | 1 | 0.018 | ||
C12 | 2.2nF | 0402 | 1 | 0.008 | ||
C13 | 4.7pF | 0402 | 1 | 0.168 | ||
C14 | 1.5pF | 0402 | 1 | 0.064 | ||
C15 | 1.0pF | 0402 | 1 | 0.064 | ||
C17 | 4.7μF, 16V | 0805 | 1 | 0.137 | ||
C18 | 220nF | 0402 | 1 | 0.036 | ||
D1 | Zener 4.7V | MINIMELF | 1 | 0.026 | ||
D2 | Schottky | MICROMELF | 1 | 0.060 | ||
L1 | 3.9nH | 0402 | 1 | 0.017 | ||
L2 | 2.7nH | 0402 | 1 | 0.017 | ||
L3 | 8.2nH | 0402 | 1 | 0.036 | ||
Q1 | 16MHz, 10ppm | 1210 | 1 | 0.758 | ||
R0 | 100Ω | 1206 | 1 | 0.014 | ||
R1,R2 | 220kΩ | 1206 | 2 | 0.014 | 0.028 | |
R3,R4 | 22kΩ, 1% | 0402 | 2 | 0.016 | 0.032 | |
R5,R6 | 2.2kΩ | 0402 | 2 | 0.010 | 0.020 | |
U1 | ATTINY84A-MU | MLF20 | 1 | 1.010 | ||
U4 | ANTENNA | ANTENNA | 1 | 0.403 | ||
V1 | AAT3220 | SOT23 | 1 | 0.136 | ||
Preis ohne/mit MwSt | 5.189 | 6.175 | ||||
U2 | NRF24L01+ | QFN20 | 1 | ebay | 0.860 | |
U3 | HMC5883L | LPCC16 | 1 | ebay | 1.590 | |
PCB Oshpark | 0.820 | |||||
Preis aller Komponenten | 9.445 | |||||
Version V07 | ||||||
D1 | Zener 5.6V | MINIMELF | 1 | 0.026 | unverändert | |
D2' | Brückengleichrichter DLPA006 160mA | SOT-363 | 1 | 0.408 | statt 0.060 | |
R1/2' | 470kΩ | 1206 | 1 | 0.014 | statt 0.028 | |
R7 | 27kΩ, 1% | 0402 | 1 | 0.016 | zusätzlich | |
Zusatzkosten | 0.350 | 0.417 | ||||
Preis aller Komponenten | 9.862 | |||||
Version V09 | ||||||
R1←R0 | 100Ω 500V | 1206 | 1 | 0.033 | statt 0.014 | |
R2 | 470kΩ 500V | 1206 | 1 | 0.033 | statt 0.014 | |
Zusatzkosten | 0.038 | 0.045 | ||||
Preis aller Komponenten | 9.907 |
Eine erste Version einer Betriebsstundensoftware findet sich unter http://github.com/wangnick/bsz. Die entsprechende Internet-Gateway-Software für die Basisstation ist noch in Arbeit. Auch eine Kalibrierfunktion für den Stromverbrauch fehlt noch.
Ein erster Versuch eines Bootloaders findet sich unter https://github.com/wangnick/mirfboot. Der dazugehörige Bootserver ist noch in Arbeit.