Pentek 6230 Operating Manual page 201

1
SCL
0
SDA
START BY
MASTER
Figure 2a. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register
1
SCL
0 1
SDA
START BY
MASTER
1
SCL
SDA 0 1
START BY
MASTER
A read operation is then performed consisting of the serial bus
address, R/W bit set to 1, followed by the data byte read from
the data register. This is shown in Figure 2c.
2. If the Address Pointer Register is known to be already at the
desired address, data can be read from the corresponding
data register without first writing to the Address Pointer
Register, so Figure 2b can be omitted.
NOTES
1. Although it is possible to read a data byte from a data register
without first writing to the Address Pointer Register, if the
Address Pointer Register is already at the correct value, it is
not possible to write data to a register without writing to the
Address Pointer Register because the first data byte of a write is
always written to the Address Pointer Register.
2. In Figures 2a to 2c, the serial bus address is shown as the
default value 01011(A1)(A0), where A1 and A0 are set by
the three-state ADD pin.
MEASUREMENT INPUTS
The ADM1024 has nine external measurement pins that can be
configured to perform various functions by programming the
Channel Mode Register.
REV. A
1 0 1 A0
1 A1
FRAME 1
SERIAL BUS ADDRESS BYTE
SCL (CONTINUED)
SDA (CONTINUED)
0 1 1 A1 A0
R/W
FRAME 1
SERIAL BUS ADDRESS BYTE
Figure 2b. Writing to the Address Pointer Register Only
0 1 1 A1 A0
R/W
FRAME 1
SERIAL BUS ADDRESS BYTE
Figure 2c. Reading Data from a Previously Selected Register
9 1
D6 D4
R/W D7 D5
ACK. BY
ADM1024
ADDRESS POINTER REGISTER BYTE
1
D7 D6 D5 D4 D3
FRAME 3
DATA BYTE
9 1
D7 D6 D5 D4
ACK. BY
ADM1024
FRAME 2
ADDRESS POINTER REGISTER BYTE
9 1
D6
D7 D5 D4
ACK. BY
ADM1024
FRAME 2
DATA BYTE FROM ADM1024
Pins 13 and 14 are dedicated to temperature measurement, while
Pins 15, 16, and 19 are dedicated analog input channels. Their
function is unaffected by the Channel Mode Register.
Pins 5 and 6 can be individually programmed as analog inputs,
or as digital fan speed measurement inputs, by programming
Bits 0 and 1 of the Channel Mode Register.
Pins 17 and 18 can be configured as analog inputs or as inputs
for external temperature-sensing diodes by programming Bit 2
of the Channel Mode Register.
Bit 3 of the Channel Mode Register configures the internal V
measurement range for either 3.3 V or 5 V.
Bits 4 to 6 of the Channel Mode Register enable or disable Pins
22 to 24, when they are configured as interrupt inputs by setting
Bit 7 of the Channel Mode Register. This function is controlled
for Pins 20 and 21 by Bits 6 and 7 of Configuration Register 2.
Bit 7 of the Channel Mode Register allows the processor core
voltage ID bits (VID0 to VID4, Pins 24 to 20) to be reconfigured
as interrupt inputs.
A truth table for the Channel Mode Register is given in Table II.
–9–
ADM1024
9
D3 D2 D1
D0
ACK. BY
ADM1024
FRAME 2
9
D2 D1 D0
ACK. BY STOP BY
ADM1024 MASTER
9
D3 D2 D1
D0
ACK. BY STOP BY
ADM1024 MASTER
9
D3 D2 D1 D0
NO ACK. STOP BY
BY MASTER MASTER
CC