as5055 austriamicrosystems, as5055 Datasheet - Page 15

• Manufacturer Part Number: as5055
• Description: Low Power 12 Bit Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5055
Data Sheet – SPI Interface
11 SPI Interface
The 16 bit SPI Interface enables read / write access to the register blocks and is compatible to a standard micro
controller interface. The SPI module is active as soon as /SS pin is pulled low. The AS5055 then reads the digital
value on the MOSI (master out slave in) input with every falling edge of SCK and writes on its MISO (master in slave
out) output with the rising edge. After 16 clock cycles /SS has to be set back to a high status in order to reset some
parts of the interface core.
The SPI Interface can be set into two different modes - 3-wire mode or 4-wire mode.
Note: The wire mode selection is read in during the POWER-UP state and can be changed with a power on reset or a
software reset
The SPI Interface can be set into two different modes - 3-wire mode or 4-wire mode.
Table 6. Wire Mode Selection
11.1 SPI Interface Signals (4-Wire Mode, Wire_mode = 1)
The AS5055 only supports slave operation mode. Therefore SCK for the communication as well as the /SS signal has
to be provided by the test equipment. The following picture shows a basic interconnection diagram with one master
and an AS5055 device and a principle schematic of the interface core.
Figure 10. SPI Interface Connection
Because the interface has to decode the sent command before it can react and provide data the response of the chip
to a specific command applied at a time T can be accessed in the next transmission cycle ending at T + TCOM.
The data are sent and read with MSB first. Every time the chip is accessed it is sending and receiving data.
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wire_mode = LO
wire_mode = HI
command.)
3-wire mode
4-wire mode
Wire Mode Selection (pad 14)
Revision 1.2
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