JeeLabs Precision RTC Module

Looks good! Just a suggestion but instead of:

switch (val.toString) {
    case "Monday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(1))]);
      break;
    case "Tuesday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(2))]);
      break;
    case "Wednesday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(3))]);
      break;
    case "Thursday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(4))]);
      break;
    case "Friday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(5))]);
      break;
    case "Saturday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(6))]);
      break;
    case "Sunday":
      I2C1.writeTo(i2c_address,[0x03, (dec2bcd(7))]);
      break;
    default:
      print(text,"Not a valid day");
    return;
  }

What about:

 var days = ["Monday","Tuesday",...];
 var idx = days.indexOf(val);
  if (idx<0) {
    print("Not a valid day");
  } else {
   I2C1.writeTo(i2c_address,[0x03, (dec2bcd(1+idx))]);
 }
}

It's maybe a bit more compact...