Data Translation DT9837, Руководство пользователя

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Appendix C
142
Writing to EEPROM
On the DT9837A, DT9837B, and DT9837C modules, the Open Layers Control Panel has
controls for setting the following parameters, which are stored in 8 consecutive bytes of
EEPROM:
• Channel 0, 1, 2 and 3 Coupling type. The values AC or DC are stored as constants for these
controls.
• Channel 0, 1, 2 and 3 Current Source. The values INTERNAL, EXTERNAL or DISABLED
are stored as constants for these controls. Note that while the control panel has only two
states (Enabled and Disabled), three states are actually defined, as follows:
−
INTERNAL = Enabled (used by the control panel)
−
EXTERNAL = Disabled
−
DISABLED = Disabled (used by the control panel)
• High power mode. You can keep high power mode always turned on or turn off high
power mode (the default setting). Turning off the high-power circuitry helps to conserve
power, which may be useful when the module is used with a laptop. However, to ensure
that the module is warmed up and that any settling time errors of the IEPE current source
are minimized, it is recommended that you keep the module’s high-power circuitry
always turned on.
To keep high power mode always on, set the value of this control to True. To turn off high
power mode, set the value of this control to False.
These controls may also be “uninitialized” if for some reason, the module skipped the
post-manufacturing initialization process.
To access the storage locations programmatically, use the olDiagReadReg() and
olDiagWriteReg() functions. The following code shows the location of these controls in the
register map:
#define EEPROM_MEM_BASE 0x100000
// Coupling storage offsets relative to the base address for the
// four analog input channels
const EEPROM_OFFSET_COUPLING_0 = 0x0020;
const EEPROM_OFFSET_COUPLING_1 = 0x0021;
const EEPROM_OFFSET_COUPLING_2 = 0x0022;
const EEPROM_OFFSET_COUPLING_3 = 0x0023;
// Current source storage offsets relative to the base address for
// the four analog input channels
const EEPROM_OFFSET_CURRENT_SOURCE_0 = 0x0024;
const EEPROM_OFFSET_CURRENT_SOURCE_1 = 0x0025;
const EEPROM_OFFSET_CURRENT_SOURCE_2 = 0x0026;
const EEPROM_OFFSET_CURRENT_SOURCE_3 = 0x0027;
// High power mode offset relative to the base address
const EEPROM_OFFSET_POWER_OVERRIDE_REG = 0x0040;