DMM Analog front end with Inrush
Function Description
1.
MPU serial I/O function overview
1.1 Introduction
ES51970 configures a 3-wire serial I/O interface to external microprocessor unit (MPU).
The SDATA pin is bi-directional and SCLK & DATA_NEW are unilateral. The SDATA pin
is configured by open-drain circuit design. The DATA_NEW is used to check the data
buffer of ADC ready or not. When the ADC conversion cycle is finished, the DATA_NEW
pin will be pulled high until MPU send a valid read command to ES51970. After the first ID
byte is confirmed, the DATA_NEW will be driven to low until the next ADC conversion
finished again.
The data communication protocol is shown below. The write protocol is configured by an
ID byte with four command bytes. The read protocol is configured by an ID byte with ten
data bytes.
Write command:
ID byte, Write control byte1, Write control byte2, Write control byte3, Write control byte4
START BIT
1
1
0
0 1
0
B
U
Z 0
A
C
K
A
C
K
A
C
K
A
C
K
A
C
K
STOP BIT
ES51970(6000counts)
WRITE
Read command:
ID byte, Read data byte1, Read data byte2 ~ Read data byte9, Read data byte10
START BIT
1
1
0
0 1
B
U
0 Z 1
A
C
K
A
C
K
A
C
K
A
C
K
READ
A
C
K
N
A
K
STOP BIT
DATA_NEW
ADC data ready
ID code
ID code confirmed
Next ADC data ready
SDATA
1
1
0
0
1
0
1
Read command
SCLK
Start bit
Stop bit
ver. 2.8
8
12/01/12
CYRUSTEK [ Cyrustek corporation ]
