Monday, December 15, 2014

LCD Serial Backpack v8 Update

The LCD Serial Backpack (BPK-000), in continuous production since 1994, has been updated to version 8. The firmware is unchanged; the pcb layout has been improved and the circuit tweaked. The updated model is now made in the USA.

Hardware Changes

BPK-000 v8 is a drop-in replacement for previous versions. Here's a quick visual comparison of versions 7 and 8:

  1. The 5-pin power/serial header is unchanged, and located in the same position relative to the LCD-connection pads. 
  2. The DIP switch for configuring LINES and BPS settings has been replaced by cuttable jumpers (defaulting to multiline, 9600bps). For 1-line displays, cut the LINES jumper; for 2400bps, cut the BPS jumper. 
  3. Pins 1-14 of the LCD connections are unchanged. Pins 15 and 16 have been added to allow hookup of common LED backlights (pin 15= A/+5V, pin 16=K/GND). 
  4. Pads have been added for a series resistor in the GND leg of the LED backlight circuit. Installing a resistor (typical values 10-100Ω) here will complete the backlight circuit.

Circuit Changes

The LCD Serial Backpack circuit was originally built around the PIC16C54 microcontroller. It was later migrated to PIC16C620 to take advantage of in-circuit programming and built-in low-voltage reset options that simplified manufacturing. 
Version 8 is based on the PIC16F54, the flash-memory version of the 'C54. Version 8 uses an external low-voltage reset, a Microchip  MCP131T-450E/TT. 
The startup delay with the external reset is slightly longer (+70ms) than the v7's built-in reset. 

Firmware: No Changes

The firmware was not changed during this update; it is identical to the PIC16(C/F)54 devices the we sell for OEM integration. It is functionally the same as the PIC16C620 version.

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