User`s guide

16 • Registers Format
3.5 A/D Channel Read Back Register
The AD channel setting can be read back from this register.
Address: BASE + 6h
Attribute: read only
Data Format:
Bit 7 6 5 4 3 2 1 0
BASE+6h AS3 AS2 AS1 AS0 CN3 CN2 CN1 CN0
BASE+7h -- -- -- -- -- -- -- --
Where:
CNn: channel number
ASn: Auto scan channel number.
There are 8 bits in this register. Under non-auto scan mode, the 4 LSBs
(CN0~CN3) show the channel number setting and the 4 MSBs (AS3~AS0)
is all ‘0’. Under auto-scan mode, the 4LSBs record the ending channel
number. The 4 MSBs is the selected channel, and the value will increase
automatically if any A/D trigger signal is inserted.
3.6 A/D Input Signal Range Control Register
The A/D range register is used to adjust the analog input ranges. This
register directly controls the PGA (programmable gain amplifier). When a
different gain value is set, the analog input range will be changed to the its
corresponding value.
Address: BASE + 8h
Attribute: write only
Data Format:
Bit 7 6 5 4 3 2 1 0
BASE+8h X X X X X G2 G1 G0
BASE+9h X X X X X X X X
The relationship between gain setting and its corresponding A/D range is
listed in the table below.
G2 G1 G0 GAIN Analog Input Range
Gain Code used in
Software Library
0 0 0 1 ±10V AD_B_10_V
0 0 1 2 ±5V AD_B_5_v
0 1 0 4 ±2.5V AD_B_2_5_V
0 1 1 8 ±1.25V AD_B_1_25_v
1 0 0 16 ±0.625V AD_B_0_625_V