Displays and Logs RF messages

This device is a substitute for the Weather Logger in that it receives all my messages in the 433 MHz band, displays them and logs them. It differs in that it is portable and therefore lacks the hard-wired inputs of the Weather Logger.

It is battery-operated, self contained, and uses a 4 row by 20 column character OLED display. It consists of an external (to avoid interference) RF receiver with a wood base and three sub-assemblies which are housed in a metal clamshell case with a sloping cream-colored top. The top has a 20-column by 4 row blue OLED character display, and a 5-button rosette, which are connected via an interface board to the brown base by a ribbon cable. The base has three sub-assemblies: Power, Signal Conditioning, and Logging/Display. A. The Power sub-assembly has a 3400 MAH Li-Ion cell which has a switch-mode charger. The recommended charging power supply is the Challenger 12V, 3A with 2 pigtails. When the battery is fully charged, the power consumption is 1.2W. It can run the Logger for about 19 hours on a charge. It also has an on-off switch and an attenuator to measure the charging voltage. The power must be on to charge. The battery connects to the Logging/Display when on. The Logging/Display (C) provides +5V power to the Signal Conditioner from an internal booster. B. The Signal Conditioner sub-assembly uses a Picaxe 28X2. It converts analog inputs to ASCII in volts with decimal point . There are three sets of inputs: 1. Power Monitoring: Charging voltage and Battery voltage. 2. Rear panel: 3 jacks Green, Blue and Orange have 3 switched ranges: Up=28V, Center=52V, Down=12V. Scaling is automatically corrected in the conversion. A 4.096V reference is used. The White jack is direct 2V using a 2.048V reference. Analog inputs are digitized and transferred to the Logging/Display when it sends a command. 3. RF signals via 9-pin male jack. These are already digitized and verified messages are immediately transferred to the Logging/Display unmodified. C: The Logging/Display uses an Pololu A-Star 32u4 Prime LV. which is compatible with the Arduino IDEl . The 32u4 was selected over the Atmel328P-based UNO because its additional 512 bytes SRAM was needed. The Pololu A-Star was selected over the Arduino Leonardo because it runs directly from the battery. The A-Star is covered by full-size SD logger shield, which also has a real-time clock-calendar and an unused added serial EEPROM. The hard-wiring on the shield and A-star peculiarities severely constrained the choice of pins. The I2C RTC is hard-wired to pins 2&3 on the A-Star. The SD and the EEPROM are SPI hard-wired on the shield to pins 11-13. 10 is hard wired for the SD select. Pin 8 was home-wired to 8 for the EEPROM select. Serial input on the 32u4 needs 8 and up, so 9 must be used. There are additional pins on the A-Star but the shield makes them physically inaccessible. A0 and A1 are used for the buttons, This results in using 5,7 and A2-A5 for the display and 6 for the serial output. 4 is unused.

Block Diagram

Front:

These are the photos of the finished clock.

Here is the Picaxe program.

Here is the Arduino sketch.

Here are the circuit diagrams.