Hardware Reference
In-Depth Information
CE
Write operation
SCK
Control byte
Address byte = 0x80
A
7
A
0
D
7
D
0
SDI
High Z
SDO
Read operation
Address byte = 0x02
A
7
A
0
SDI
D
7
D
0
D
7
D
0
D
7
D
0
SDO
Figure 10.15c
■
SPI multiple-data-byte transfer
Step 4
Read the temperature result low byte. Likewise, write a dummy byte into the SSPBUF
register to shift in the temperature low byte.
Step 5
Pull the CE pin to low so that a new transfer can be started.
The TC72 has four internal registers: control register, LSB temperature, MSB temperature,
and manufacturer ID. Their contents are shown in Table 10.4.
Read
Address
Write
Address
Value on
POR/BOR
Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Control
0x00
0x80
0
0
0
OS
1
0
0
0
SHDN
2
0x05
LSB temperature
0x01
N/A
T1
T0
0
0
0
0
0
0
0x00
MSB temperature
0x02
N/A
T9
T8
T7
T6
T5
T4
T3
T2
0x00
Manufacturer ID
0x03
N/A
0
1
0
1
0
1
0
0
0x54
1
OS is one-shot
2
SHDN is shutdown
Table 10.4
■
Register for TC72
C
ONTROL
R
EGISTER
The control register is read-/writable and is used to select the shutdown, continuous, or
one-shot conversion operating mode. The temperature conversion mode selection logic is
shown in Table 10.5.
At power-up, the SHDN bit is 1. Thus, the TC72 is in the shutdown mode at startup. The shut-
down mode disables the temperature conversion circuitry; however, the serial I/O communication
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