AS3935-BQFT ams, AS3935-BQFT Datasheet - Page 14

• Manufacturer Part Number: AS3935-BQFT
• Description: Interface - Specialized
• Manufacturer: ams

Specifications of AS3935-BQFT

• Rohs: yes
• Operating Supply Voltage: 2.4 V to 5.5 V
• Supply Current: 100 mA
• Maximum Power Dissipation: 0.1 W
• Mounting Style: SMD/SMT
• Package / Case: MLPQ-16
• Supply Voltage - Max: 5.5 V

AS3935
Datasheet - D e t a i l e d D e s c r i p t i o n
8.4 Serial Peripheral Interface (SPI)
This 4-wire standard SPI interface (Mode 1) can be used by the Microcontroller (μC) to program the AS3935. To enable the SPI as data
interface, the Select Interface (SI) has to be set to low (GND).
The maximum clock operation frequency of the SPI is 2MHz.
Note: The clock operation frequency of the SPI should NOT be identical to the resonance frequency of the antenna (500kHz), in order to
Table 10. Serial Data Interface (SDI) Pins
Note: MISO is set to tristate if CS is high. In this way more than one device can communicate on the same MISO bus.
8.4.1 SPI Command Structure
To activate this SPI, the CS has to be set to low. A SPI command consists of two bytes serial command and the data are sampled on the falling
edge of SCLK (CPHA=1). The next table shows command structure, from the MSB (B15) to LSB (B0). The command stream has to be sent to
the SPI from the MSB (B15) to the LSB (B0).
The first two bits (B15 and B14) define the operating mode. There are two modes available – Read and Write/Direct command.
Table 11. Bits B15, B14
In case a write or read command happens, then the next 5 bits (B13 to B9) define the register address, which has to be written respectively read,
as shown in the table below. The direct command is performed with a write operation
Table 12. Bits B13 to B9
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B15
MODE
B13
…
…
Name
0
0
0
0
0
0
0
0
1
1
MOSI
MISO
SCLK
CS
minimize the on board 500kHz noise.
B14
B15
0
0
B13
B12
…
…
0
0
0
0
0
0
0
0
1
1
Register Address / Direct Command
B12
Digital Output
Digital Input
Digital Input
Digital Input
Signal
B11
B11
…
…
0
0
0
0
0
0
0
0
0
0
B10
B14
0
1
B10
…
…
B9
0
0
0
0
1
1
1
1
0
0
Signal Level
CMOS
CMOS
CMOS
CMOS
B8
Revision 1.2
B9
…
…
0
0
1
1
0
0
1
1
0
1
B7
Serial data output from the AS3935 to the external unit
Serial data input from the external unit to the AS3935
B6
(see Send Direct Command Byte on page
B8
…
…
0
1
0
1
0
1
0
1
1
0
WRITE / DIRECT COMMAND
Clock for serial data read and write
B5
Chip Select (Active Low)
Register Data
B4
READ
Mode
Description
Read / Write Register
B3
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x31
0x32
B2
…
…
16).
B1
14 - 27
B0