Service Manual
Description of the LC2 electronics
23.07.07 Kr/Rei
Page 5(6)
30-34-00-745
If the voltage drops below a certain limit, the user is alerted by the battery symbol in the LCD. If the
next threshold is undershot, "bAtt” is displayed and weighing is no longer possible.
Resonator
A ceramic 8 MHz resonator is used as a time basis for all functions of the module.
LC module bus
The LC module bus establishes the connection to the LC display module and at the same time forms
the adjustment interface. The unregulated supply voltage is made available on the bus. All relevant
data is exchanged via a data line and a clock pulse line.
Pin
Function
Note
1
SCL
Serial Clock TWI
2
GND
Ground
3
SDA
Serial Data TWI
4
Vin
Battery/power supply voltage
Programming interface
The programming interface is a 10-pin interface, which is only accessible after opening the housing.
The housing is secured with a seal that must be destroyed to open the housing. Warning: If the seal is
destroyed, verification is no longer valid. A special seca service adapter is required to access the
programming interface.
The service interface can be used to:
- supply the unregulated supply voltage
- measure the regulated voltage for the electronics
- delete and write new data to the flash memory and the EEPROM of the microcontroller
Programming
The microcontroller contains two types of non-volatile memories that are used for various purposes in
the module. The following memory types are provided:
Type of memory
Size
Flash memory
8 Kbytes
EEPROM
512 bytes
The flash memory holds the firmware for the microcontroller. During programming, the data is written
to the flash memory via the 10-pin programming interface. All scale-specific parameters required by
the display and for measuring the weight are stored in the EEPROM. Data is written to the EEPROM
during the adjustment process. The display automatically retrieves all the parameters it needs from the
EEPROM of the LC weight module via the LC module bus. Both memories are protected by an LRC
checksum. A data error in either of the two memories cannot be remedied during the operation and
causes a permanent fault indication. Weighing operations are then no longer possible. Once the scale
has been programmed, both memories are protected against reading out and modifying data via the
programming interface. Any modification of the data first requires that both memories are completely
cleared.
Adjustment
To ensure that the scale functions properly, the LC weight value module must be adjusted before it is
set into operation. During the adjustment, the A/D converter supplies measured values to the
adjustment processor via the LC module bus. The adjustment processor determines the adjustment
data for the LC weight module from the values measured for different loads on the scale. If you wish to
configure individual temperature compensation, the scale must be measured with a load and without a
load at temperatures on different ends of the range. The adjustment data is then stored on the
EEPROM.
