AD7879ACPZ-RL Analog Devices Inc, AD7879ACPZ-RL Datasheet - Page 30

• Manufacturer Part Number: AD7879ACPZ-RL
• Description: IC ADC 12BIT CTLR TOUCH 16LFCSP
• Manufacturer: Analog Devices Inc
• Type: Touch Screen Controller: 4-Wire Resistiver

Specifications of AD7879ACPZ-RL

• Resolution (bits): 12 b
• Data Interface: I²C
• Package / Case: 16-LFCSP
• Mounting Type: Surface Mount
• Voltage - Supply: 1.6 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Voltage Supply Source: Single Supply
• Sampling Rate (per Second): 105k
• Sampling Rate: 105kSPS
• Supply Voltage Range - Analog: 1.6V To 3.6V
• Supply Current: 480µA
• Digital Ic Case Style: CSP
• No. Of Pins: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7879
SERIAL INTERFACE
The AD7879 is available with an serial peripheral interface
(SPI). The AD7879-1 is available with an I
interface. Both parts are the same, with the exception of the
serial interface. It is recommended not to write to addresses
outside the register map.
SPI INTERFACE
The AD7879 has a 4-wire SPI. The SPI has a data input pin
(DIN) for inputting data to the device, a data output pin
(DOUT) for reading data back from the device, and a data
clock pin (SCL) for clocking data into and out of the device.
A chip select pin ( CS ) enables or disables the serial interface.
CS is required for correct operation of the SPI interface. Data
is clocked out of the AD7879 on the negative edge of SCL and
data is clocked into the device on the positive edge of SCL.
SPI Command Word
All data transactions on the SPI bus begin with the master
taking CS from high to low and sending out the command
word. This indicates to the AD7879 whether the transaction
is a read or a write, and gives the address of the register from
which to begin the data transfer. The bit map in
the SPI command word.
Table 22.
MSB
15
1
SCL
DIN
CS
14
NOTES
1. DATA BITS ARE LATCHED ON SCL RISING EDGES. SCL CAN IDLE HIGH OR LOW BETWEEN WRITE OPERATIONS.
2. ALL 32 BITS MUST BE WRITTEN: 16 BITS FOR CONTROL WORD AND 16 BITS FOR DATA.
3. 16-BIT COMMAND WORD SETTINGS FOR SERIAL WRITE OPERATION:
1
CW[15:11] = 11100 (ENABLE WORD)
CW[10] = 0 (R/W)
CW[9:0] = [AD9, AD8, AD7, AD6, AD5, AD4, AD3, AD2, AD1, AD0] (10-BIT MSB JUSTIFIED REGISTER ADDRESS)
CW
15
t
2
13 12
1
1
t
1
CW
ENABLE WORD
14
2
0
t
3
CW
13
3
11
0
CW
12
4
10
R/W
CW
11
5
t
R/W
CW
4
10
6
16-BIT COMMAND WORD
CW
9:0
Register address
9
2
C®-compatible
7
CW
8
Table 22
8
Figure 38. Single Register Write, SPI Timing
CW
7
t
5
9
REGISTER ADDRESS
CW
shows
6
10
LSB
Rev. 0 | Page 30 of 36
CW
5
11
CW
4
12
CW
3
Bits[15:11] of the command word must be set to 11100 to
successfully begin a bus transaction.
Bit 10 is the read/write bit; 1 indicates a read, and 0 indicates
a write.
Bits[9:0] contain the target register address. When reading or
writing to more than one register, this address indicates the
address of the first register to be written to or read from.
Writing Data
Data is written to the AD7879 in 16-bit words. The first word
written to the device is the command word, with the read/write
bit set to 0. The master then supplies the 16-bit input data-word
on the DIN line. The AD7879 clocks the data into the register
addressed in the command word. If there is more than one word
of data to be clocked in, the AD7879 automatically increments
the address pointer and clocks the next data-word into the
following register.
The AD7879 continues to clock in data on the SDA line until
either the master finishes the write transition by pulling CS
high, or until the address pointer reaches its maximum value.
The AD7879 address pointer does not wrap around. When it
reaches its maximum value, any data provided by the master
on the DIN line is ignored by the AD7879.
13
CW
2
14
CW
1
15
CW
0
16
D15
17
D14
18
D13
19
16-BIT DATA
D2
30
D1
t
8
31
D0
32