Datasheet

AD7747
Rev. 0 | Page 14 of 28
REGISTER DESCRIPTIONS
The master can write to or read from all of the AD7747 registers
except the address pointer register, which is a write-only
register. The address pointer register determines which register
the next read or write operation accesses. All communications
with the part through the bus start with an access to the address
pointer register. After the part has been accessed over the bus
and a read/write operation is selected, the address pointer
register is set up. The address pointer register determines from
or to which register the operation takes place. A read/write
operation is performed from/to the target address, which then
increments to the next address until a stop command on the bus
is performed.
Table 8. Register Summary
Address
Pointer Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Register (Dec) (Hex) Dir Default Value
– – – – – RDY RDYVT RDYCAP Status 0 0x00 R
0 0 0 0 0 1 1 1
Cap Data H 1 0x01 R Capacitive channel data—high byte, 0x00
Cap Data M 2 0x02 R Capacitive channel data—middle byte, 0x00
Cap Data L 3 0x03 R Capacitive channel data—low byte, 0x00
VT Data H 4 0x04 R Voltage/temperature channel data—high byte, 0x00
VT Data M 5 0x05 R Voltage/temperature channel data—middle byte, 0x00
VT Data L 6 0x06 R Voltage/temperature channel data—low byte, 0x00
CAPEN – CAPDIFF – – – – – Cap Setup 7 0x07 R/W
0 0 0 0 0 0 0 0
VTEN VTMD1 VTMD0 EXTREF – – VTSHORT VTCHOP VT Setup 8 0x08 R/W
0 0 0 0 0 0 0 0
– – – – EXCDAC EXCEN EXCLVL1 EXCLVL0 EXC Setup 9 0x09 R/W
0 0 0 0 0 0 1 1
VTFS1 VTFS0 CAPFS2 CAPFS1 CAPFS0 MD2 MD1 MD0 Configuration 10 0x0A R/W
1 0 1 0 0 0 0 0
DACAENA – DACA—6-Bit Value Cap DAC A 11 0x0B R/W
0 0 0x00
DACBENB – DACB—6-Bit Value Cap DAC B 12 0x0C R/W
0 0 0x00
Cap Offset H 13 0x0D R/W Capacitive offset calibration—high byte, 0x80
Cap Offset L 14 0x0E R/W Capacitive offset calibration—low byte, 0x00
Cap Gain H 15 0x0F R/W Capacitive gain calibration—high byte, factory calibrated
Cap Gain L 16 0x10 R/W Capacitive gain calibration—low byte, factory calibrated
Volt Gain H 17 0x11 R/W Voltage gain calibration—high byte, factory calibrated
Volt Gain L 18 0x12 R/W Voltage gain calibration—low byte, factory calibrated