Difference between revisions of "MicroBoSL"
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Now we need to test the MOSFET. Applying a 50 Ω load connected on the high side to 5V, the MOSFET was able to turn this on and off. Thus, the MOSFET is at least capable of driving a 100 mA load, and it is suspected that an even greater load is possible. | Now we need to test the MOSFET. Applying a 50 Ω load connected on the high side to 5V, the MOSFET was able to turn this on and off. Thus, the MOSFET is at least capable of driving a 100 mA load, and it is suspected that an even greater load is possible. | ||
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| + | Notably what hasn't been tested is the pin interfaces on the external side of the device. This includes the hall effect sensors. However this is very simple circuitry, direct connections to Arduino pins, so issues should be had. | ||
Revision as of 00:48, 20 January 2021
Here we will document the design of the microBoSL board , a miniaturized version of the BoSL board.
Key changes from the BoSL board to the microBoSL board:
- Upgrade SIM7000 to smaller SIM7090
- Remove much of the connectivity to achieve smaller profile
- Add NFC
- Make board much smaller. No more than 30 mm in width.
- Removed MS5803
To do this many components will have their parts changed to a smaller footprint version.
These substitutions include:
- Many passives -> mostly 0603
- ATmega328P-AU -> ATmega328P-MMH
- FT232RL -> FT232RQ
- 74HC126D -> 74HC126PW-Q100
- MCP7940NT-I/SN -> MCP7940NT-I/MNY
- MCP1700-3302E_SOT89 -> MCP1700-3302E_SOT23
20th January 2020
The micro BoSL is here:
MicroBoSL Front
A quick test reveals that programs are able to be uploaded to the device. This verifies the status of the MCU and the USB-TTL converter.
Next is to test the RTC. A quick test with indicates that this too is working well. An issue is had a bit with the LEDs. These tend to stay on even after the USB power is removed. This is an issue as it could cause extended power draw. A work around found was to hold the reset button for 3 seconds until all the LEDs turned off after this they did not seem to turn on again.
A test using the RTC persistence time keeping indicates that the board can operate on battery power hence, the o-ring and power delivery circuit does indeed work.
Now we need to test the MOSFET. Applying a 50 Ω load connected on the high side to 5V, the MOSFET was able to turn this on and off. Thus, the MOSFET is at least capable of driving a 100 mA load, and it is suspected that an even greater load is possible.
Notably what hasn't been tested is the pin interfaces on the external side of the device. This includes the hall effect sensors. However this is very simple circuitry, direct connections to Arduino pins, so issues should be had.
