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ReadMe file for Arduino-Based Power Outage Logger board v1.1 https://github.com/JChristensen/PowerOutageMonitor_HW Jack Christensen Sep 2012 This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. ================================================================================ This repository contains the following for the Power Outage Logger board: Schematic Eagle Files Bill of materials (below) An Arduino sketch for the board can be found at: https://github.com/JChristensen/PowerOutageMonitor_SW ================================================================================ Assembly notes and options 1. The board is intended to be powered by either a 5V or a 7-12V AC adapter. When using a 5V adapter, it MUST BE REGULATED; in this case, C1, C2, D1 and U2 do not need to be installed. Set the PWR SEL jumper (JP1) to DIRECT when using a 5V regulated adapter. 2. When disconnected from the power, certain 5V regulated adapters may emit a power blip that the RTC interprets as a power-up event. This results in the power-down and power-up timestamps being identical even if the power is left off for several minutes. To eliminate this, power the RTC from an MCU pin by selecting MCU power via the RTC PWR jumper (JP2). This is supported by the sketch referenced above. It is also recommended to set the ATmega328P brown-out detector to 4.3V by setting the extended fuse byte to 0x04. Note that when the RTC is powered from the MCU pin, any MCU reset will cause a power outage to be logged, whether or not is is associated with an actual power outage. 3. The Tinsharp TC1602A-09T 16x2 LCD display uses an LED backlight that requires only 15mA at 5V. This means that a current-limiting resistor is not needed (use a jumper in place of R5), and that the backlight can be powered from an MCU pin. Do not use displays that require more than 20mA to operate the backlight. Note also that some displays will require a non-zero value for R5 if their backlight operates on less than 5V. 4. The board includes optional provisions for an on-board temperature sensor and associated pullup resistor (U3, R6). An optional three-position terminal block can also connect to an off-board sensor. The Arduino sketch referenced above contains no code for these optional sensors. 5. Photocell PC1 is used to adjust the display backlight brightness to match the ambient light level. The Arduino sketch above uses the internal AVR pullup resistor in association with PC1, but if this does not result in satisfactory adjustment of the backlight, then the internal pullup can be disabled and an alternate resistor can be installed at R4. ================================================================================ Power Outage Logger Board Bill of Materials Part Value Device C1 47uF Radial lead electrolytic, 16V, 2 mm lead spacing C2 100nF 50V MLCC, 0.1 in. lead spacing C3 47uF Radial lead electrolytic, 16V, 2 mm lead spacing C4 100nF 50V MLCC, 0.1 in. lead spacing C5 100nF 50V MLCC, 0.1 in. lead spacing C6 100nF 50V MLCC, 0.1 in. lead spacing C7 100nF 50V MLCC, 0.1 in. lead spacing C8 27pF 50V MLCC, 0.1 in. lead spacing C9 27pF 50V MLCC, 0.1 in. lead spacing C10 100nF 50V MLCC, 0.1 in. lead spacing D1 1N4004 Silicon rectifier D2 1N4148 Signal diode D3 5mm LED J1 2.1mm power jack JP1 Supply select 1x3 0.1 in. male header (or use jumper) JP2 RTC power select 1x3 0.1 in. male header, right angle (or use jumper) JP3 FTDI 1x6 0.1 in. male header, right angle JP4 ICSP 2x3 0.1 in. male header (OPTIONAL) PC1 CdS Photocell PCB1 MCP79412 MCP79412 RTC Breakout Board, see: https://github.com/JChristensen/rtc79412 PCB2 TC1602A-09T Tinsharp 16x2 LCD R1 10K 1/8W 5% carbon film R2 10K 3/8 in. square trimpot, Bourns 3386P or equivalent R3 330Ω 1/8W 5% carbon film R4 10K 1/8W 5% carbon film, OPTIONAL pullup resistor for photocell (sketch uses internal AVR pullup). R5 0Ω 1/8W 5% carbon film, current-limiting resistor for LCD backlight. Use a jumper with the TC1602A-09T display. Use appropriate value for other displays. R6 4.7K 1/8W 5% carbon film, OPTIONAL pullup resistor for temperature/external sensor. S1 SET Omron B3F-312X S2 UP Omron B3F-312X S3 DN Omron B3F-312X S4 RESET Omron B3F-1020 (OPTIONAL) TB1 Ext Sensor 3.5 mm x 3 terminal block, OST-TB-33.5MM or similar, OPTIONAL for external sensor connection. U1 ATmega328P-PU Microcontroller U2 78L05 5V 100mA Voltage Regulator U3 DS18B20 Temperature Sensor (OPTIONAL) Y1 16MHz 16MHz 18pF crystal