Diamond Systems HERCULES-EBX HRC400-5A128, Руководство пользователя, Страница: 92 / 123

Hercules-EBX CPU User Manual V1.02 Page 92
13.5 Analog Circuit Calibration Resources
For a board with the Data Acquisition option, the Hercules-EBX Data Acquisition circuitry
incorporates some advanced calibration features to allow the system to calibrate both the A/D
and D/A signal conversion pathways. The registers involved in controlling these calibration
features are listed below:
Register
Bit Name
Register location Signal Name Description
ADBU <All pages>Base+1:Bit 0 ADCUNI(OUT) a one sets A/D section to unipolar input mode
DABU <All pages>Base+1:Bit 2 DACUNI(OUT) a one sets D/A section to bipolar output mode
CMUXEN Page 0:Base+30:Bit 4 MUXEN4(OUT) a one enables calibration voltages multiplexer
SEDIFF <All pages>Base+1:Bit 1 ADDIFF(OUT) a one sets A/D section to differential mode
TrimDAC
Data
Page 1 : Base+28 (8-bit) TrimDAC
Data[D7-D0] Data Sent to TrimDAC
TrimDAC
Address
Page 1 : Base+29 : Bits 2-0 TrimDAC
Address [A2-A0]
Address for TrimDAC
TDACEN Page 1 : Base+30 : Bit 3 TDACEN TrimDAC Enable (when “1”) – note that this is
mutually-exclusive with EE_EN control
Table 35: Calibration Control Signal Listing
AUTO CALIBRATION TABLE:
When Register bit CMUXEN=1, the board is in auto calibration mode. When this mode is enabled,
specific calibration voltages will be fed back to analog channel inputs. There are 5 calibration settings
that can be used (named “VCAL0 – 5” below). These feedback voltages are selected based on the
“ADCH0” and “ADCH1” settings (ADCH4-2 are ignored during autocalibration):
CMUXEN SEDIFF ADCH(1/0) VCAL VOLTAGE
0
Normal Operation
1 0
0 (0/0)
0 0
1 0
1(0/1)
1 2.5mV
1 0
2 (1/0)
2 1.12V
1 0
3 (1/1)
3 4.78V
1 1 X 4 VOUT0
Table 36: Calibration Multiplexed Signal Control
Notes:
•
VCAL0 is for bipolar A/D offset adjustments
•
VCAL1 is for unipolar offset adjustments
•
VCAL2 is for full scale 0-1.25, 0-2.5, +/-1.25 and +/-2.5 modes
•
VCAL3 is for full scale 0-5, 0-10, +/-5 and +/-10 modes
•
VCAL4 is D/A VOUT0 for D/A calibration; this loops Analog output “VOUT0” back