I’m looking for BLE-enabled microcontroller that can keep time and toggle a pin (3-5V) twice a day to turn on and off another circuit. I want BLE so I can occasionally reconfigure it from a mobile phone.
My limiting factor is I want it to run on batteries for 6-12 months. I know BLE was designed to run on watch-batteries for years at a time, but I’m not certain if any common IoT platforms really do. Other than keeping track of what time it is, I need almost no processing power. Is there a good chip/platform for this kind of project?
You could get a low-power clock such as a MCP7940 and an ATtiny or simple ATmega chip and a BLE breakout. The power to the BLE is turned off when not in use, the Arduino goes into deep sleep or is even turned off completely to be wakened by the interrupt signal from the MCP7940 and then fires up the BLE to send the signal. This would run for years on a CR2032. You could add a switch to turn it on manually in order to reconfigure it. It doesn’t even need a crystal, as the internal 8MHz is sufficiently fast for this implementation and it allows the microprocessor to run at directly at battery voltage with no extra hardware.
That looks really perfect. The MCP7940 is exactly what I was looking for.
Thanks for the reply. I just this morning bookmarked the Artemis Nano as a possible solution that could over the need for a separate RTC. Also considering switching to WiFi rather than BLE and trying the ESP8266 Thing (since it could re-sync it’s clock from the internet if it loses power). Thanks for the ideas.