ADM1178-2ARMZ-R7(RevPrD) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
ADM1178-2ARMZ-R7
(Rev.:RevPrD)
(Rev.:RevPrD)
Analog Devices
ADM1178-2ARMZ-R7 Datasheet PDF : 16 Pages
| |||
ADM1178
WRITE AND READ OPERATIONS
The I2C specification defines several protocols for different
types of read and write operations. The ones used in the
ADM1178 are discussed below. The following abbreviations are
used in the diagrams:
Table 5. I2C abbreviations
S
P
R
W
A
N
START
STOP
READ
WRITE
ACKNOWLEDGE
NO ACKNOWLEDGE
QUICK COMMAND
This operation allows the master check if the slave is present on
the bus. This entails the following:
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by
the write bit (low).
3. The addressed slave device asserts ACK on SDA.
1
2
3
S
SLAVE
ADDRESS
W
A
Figure 9. Quick Command
Preliminary Technical Data
WRITE COMMAND BYTE
In this operation the master device sends a command byte to
the slave device, as follows:
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by
the write bit (low).
3. The addressed slave device asserts ACK on SDA.
4. The master sends the command byte. The command
byte is identified by an MSB =0. (An MSB =1 indicates
an Extended Register Write. See next section.)
5. The slave asserts ACK on SDA.
6. The master asserts a STOP condition on SDA to end
the transaction.
1
2
3
4
56
S
SLAVE
ADDRESS
W
A
COMMAND
BYTE
A
P
Figure 10. Command Byte Write
The seven LSBs of the command byte are used to configure and
control the ADM1178. Details of the function of each bit are
provided in Table 6.
Table 6. Command Byte Operations
Bit Default Name
Function
C0 0
V_CONT
Set to convert voltage continuously. If readback is attempted before the first conversion is complete, the
ADM1178 will ACK and return all zeros in the returned data.
C1 0
C2 0
C3 0
C4 0
C5 0
C6 0
V_ONCE
I_CONT
I_ONCE
VRANGE
N/A
STATUS_RD
Set to convert voltage once. Self-clears. I2C will NACK an attempted read until ADC conversion is complete.
Set to convert voltage continuously. If readback is attempted before the first conversion is complete, the
ADM1178 will ACK and return all zeros in the returned data.
Set to convert current once. Self-clears. I2C will NACK an attempted read until ADC conversion is complete.
Selects different internal attenuation resistor networks for voltage readback. A “0” in C4 selects a 14:1 voltage
divider. A “1” in C4 selects a 7:2 voltage divider. With an ADC full-scale of 1.902 V, the voltage at the VCC pin
for an ADC full-scale result is 26.63 V for VRANGE = 0 and 6.66 V for VRANGE = 1.
Unused
Status Read. When this bit is set the data byte read back from the ADM1178 will be the STATUS byte. This
contains the status of the device alerts. See Table14 for full details of the status byte.
Rev. PrD | Page 12 of 16
Share Link: 