AS3930 データシートの表示（PDF） - austriamicrosystems AG
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AS3930 Datasheet PDF : 32 Pages
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AS3930
Datasheet - Detailed Description
8.2.2 Serial Data Interface (SDI)
This 4-wire interface is used by the Microcontroller (µC) to program the AS3930. The maximum clock operation frequency of the SDI is 2 MHz.
Table 8. Serial Data Interface (SDI) Pins
Name
Signal
Signal Level
Description
CS
Digital Input with pull down
CMOS
Chip Select
SDI
Digital Input with pull down
CMOS
Serial Data input for writing registers, data to transmit and/
or writing addresses to select readable register
SDO
Digital Output
CMOS
Serial Data output for received data or read value of
selected registers
SCLK
Digital Input with pull down
CMOS
Clock for serial data read and write
Note: SDO is set to tristate if CS is low. In this way more than one device can communicate on the same SDO bus.
SDI Command Structure. To program the SDI, the CS signal has to go high. A SDI command is made up of two bytes serial command and
the data is sampled on the falling edge of SCLK. Table 9 shows how the command looks like, from the MSB (B15) to LSB (B0). The command
stream has to be sent to the SDI from the MSB (B15) to the LSB (B0).
Table 9. SDI Command Structure
Mode
Register Address / Direct Command
Register Data
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
The first two bits (B15 and B14) define the operating mode. There are three modes available (write, read, direct command) plus one spare (not
used), as shown in Table 10.
Table 10. Bits B15, B14
B15
B14
Mode
0
0
WRITE
0
1
READ
1
0
NOT ALLOWED
1
1
DIRECT COMMAND
In case a write or read command happens, then the next 6 bits (B13 to B8) define the register address which has to be written respectively read,
as shown in Table 11.
Table 11. Bits B13-B8
B13
B12
B11
B10
B9
B8
Read/Write Register
0
0
0
0
0
0
R0
0
0
0
0
0
1
R1
0
0
0
0
1
0
R2
0
0
0
0
1
1
R3
0
0
0
1
0
0
R4
0
0
0
1
0
1
R5
0
0
0
1
1
0
R6
0
0
0
1
1
1
R7
0
0
1
0
0
0
R8
0
0
1
0
0
1
R9
0
0
1
0
1
0
R10
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Revision 1.5
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