Prototype I2C Display Board with EEPROM

My lat­est project is a pro­to­type I2C RGB LCD dis­play board with added EEPROM and some oth­er extras.

RGB-LCD display V4.24 with 64K of EEPROM on I2C bus
RGB-LCD dis­play V4.24 with 64K of EEPROM on I2C bus

I decid­ed to do some more work on the Programmable Voltage Reference project, after a long run of test equip­ment cleanup and repairs.

A spe­cif­ic area of the project that I want­ed to tack­le was the automa­tion of the cal­i­bra­tion pro­ce­dure, and the pos­si­bil­i­ty of mul­ti­ple cal­i­bra­tion off­sets at dif­fer­ent tem­per­a­tures. Another cur­rent lim­i­ta­tion of the PVR is that it can only direct­ly dis­play the volt­age set point.
It would be fair­ly easy to cycle thru the Set point, Output volt­age, Voltage dif­fer­ence, and Mode by just using the exist­ing dis­play and update the dis­play once a sec­ond with the next val­ue. Or even ded­i­cat­ing anoth­er push-but­ton switch to cycle thru the dis­plays.
The char­ac­ters on the RGB-LCD dis­play are sig­nif­i­cant­ly small­er and will be hard­er to read from a dis­tance, but can dis­play much more infor­ma­tion all at once. Another advan­tage is using the RGB col­or back-light­ing as a sta­tus indi­ca­tor instead of the rotary encoders RGB led.

RGB-LCD display V4.24 bare circuit board from OSH Park
RGB-LCD dis­play V4.24 bare cir­cuit board from OSH Park

I changed around my exist­ing V4.23 RGB-LCD dis­play board by remov­ing the DS3231 RTC (Real Time Clock) IC and added a Microchip Technology 24LC64T‑I/SN 64K EEPROM chip. I also made some oth­er changes to the board such as adding an extra I/O pin and +5 to the JP3 head­er. The EEPROM foot­print is the same as the larg­er 128K EEPROM 24LC128‑I/SN I.C. which would make it easy to upgrade to a larg­er EEPROM in the future.

RGB-LCD display V4.24 surface mount components installed
RGB-LCD dis­play V4.24 sur­face mount com­po­nents installed

So far the board is work­ing as expect­ed, along with the Write Protect jumper. I am using the Arduino External EEPROM Library by JChristensen, along with the MCP23017 libraries from Adafruit.

I have also recent­ly designed an inline EEPROM board for my exist­ing PVR units with the 4 dig­it 7 seg­ment dis­plays.
Boards have arrived from OSH Park.

64K I2C Inline EEPROM upgrade for 7 segment PVR Version 1.0
64K I2C Inline EEPROM upgrade for 7 seg­ment PVR Version 1.0

The next part of the project is to work on chang­ing the code to use the exter­nal EEPROM, instead of the run-length encod­ed data stored on the inter­nal Teensy 3.2 EEPROM.
After fin­ish­ing the Teensy code the next task is to auto­mate the cal­i­bra­tion off­set mea­sure­ments and stor­ing the data into the exter­nal EEPROM. My cur­rent plan is to use Excel to set the PVR out­put volt­age using ser­i­al com­m’s and read­ing the volt­age with my Keithley 2015 and the inter­nal Teensy ADC. Then cal­cu­late the dif­fer­ence from the set-point and write the off­set val­ues for the out­put DAC and the Teensy inter­nal ADC using the comm port.
After cal­i­bra­tion is com­plet­ed for all 4,095 set­tings, the sys­tem will ver­i­fy the out­put with off­sets applied.

OSH Park shared I2C RGB LCD Display 4.24 W/eeprom project

EagleCAD Schematic and board files ZIP for Display V4.24 EEPROM

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