ADLINK Technology PCIe-9842, Руководство пользователя

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Calibrations 33
4 Calibrations
This chapter introduces the calibration process to minimize analog
input measurement errors and analog output errors.
4.1 Calibration Constant
The PCIe-9842 is factory calibrated before shipment by writing the
associated calibration constants to the onboard EEPROM. Every
time the system boot up, the PCIe-9842 driver will load these cali-
bration constants that minimize the error in analog input path and
analog output circuit. ADLINK provides a software API for calibrat-
ing the PCIe-9842 whenever users want to calibrate the module.
The onboard EEPROM provides four banks for calibration con-
stant storage in PCIe-9842. The bank 0, which is the default bank,
records the factory calibrated constants. Bank 0 is written protec-
tion that prevents any abnormal auto-calibration process occurred
in user’s environment. The banks 1, 2, and 3, which are user-
defined spaces, provided for user’s self-calibration constants.
When user executes the auto-calibration process, the calibration
constants will be recorded to bank 1, 2, and 3 based on user
assignment.
When the PCIe-9842 boots up, the driver will access the calibra-
tion constants and set to hardware automatically. Without user’s
assignment, the driver will load constants stored in bank 0. If user
wants to load constants from bank 1, 2, and 3, user can assign the
bank 1, 2, and 3 as the boot up bank through software. Once user
re-assigns the bank, driver will load the constants when user re-
boot the system. This setting will be recorded to EEPROM and
maintains no change until user modifies it.