IC-MR Datasheet, PDF (37/44 Pages) IC-Haus GmbH – 13-BIT S&H SIN/COS INTERPOLATOR WITH CONTROLLER INTERFACES

iC-MR 13-BIT S&H SIN/COS
preliminary
INTERPOLATOR WITH CONTROLLER INTERFACES
SERIAL I/O INTERFACE: SPI
Rev A1, Page 37/44
Register access
SPI protocol can also be used for communication
through the serial interface. Data changes at pins SLI
and SLO respectively on a falling edge at MAI and is
accepted on a rising edge at MAI. If the internal data
bus is busy due to an EEPROM readout after the reset,
for instance (i.e. if the BUSY bit is active in the status
byte), all read accesses are answered by the status
byte through the serial interface in SPI mode.
The protocol for the register read or write access con-
sists of a 3-byte transmission.
MAI
NCS
SLI
SLO
CYC & ADR(6:0)
---
OPC
---
WRITEDATA
READDATA
The third byte concludes the transmission, with which
the register data (WRITEDATA) is written through pin
SLI on a register write access. On a register read ac-
cess the requested register data (READDATA) can be
read out at pin SLO. To access the command register
the protocol can be shortened to two bytes, as the op-
code already contains the command to be executed.
Command
MAI
NCS
SLI
CYC & x60
OPC
---
SLO
---
---
---
Figure 26: Command register access
Figure 25: Register access
The decision is made as to whether a cyclic transmis-
sion or a register access takes place on the first sent
CYC bit. If registers are to be accessed, a 0 is trans-
mitted.
CYC
Code
0
1
Function
Register access
Cyclic readout
Table 67: Selecting cyclic transmission
The address is then sent as a 7-bit value. The next
transmitted byte contains the OPC transmission op-
code. This opcode comprises one bit for register read
(RD) and one bit for register write (WR) access, plus
the data for the command register (CMD).
Cyclic readout
In order to generate new position data, either
• parallel interface pin NL can be used, or
• the command register can be written to prior to cyclic
access (opcode 0x00: request for new position data).
The position data is read out on a read access from ad-
dress 0x60 when CYC = 1. The output data (addresses
0x60 to 0x6D) can be read out directly in sequence.
MAI
NCS
SLI
SLO
ADDR int
CYC & x60
---
---
STATUS
---
0x60
ST(1:0)
0x61
...
CRC(7:0)
CRC(15:8)
...
0x6C
0x6D
OPC
Code
Function
– RD WR CMD
00 0 0 0000 Request new Position data
00 0 0 0001 Write configuration in EEPROM
00 0 0 0010 Readout absolute data interface
00 0 0 0011 Trigger software reset
00 0 0 0100 CRC verification of internal configuration
00 0 0 0101 Activate error simulation ERR bit
00 0 0 0110 Deactivate error simulation ERR bit
00 0 1 0000 Writing register access
00 1 0 0000 Reading register access
Figure 27: Cyclic readout
A CRC is formed across the output data (with the poly-
nomial x ¹⁶ + x ¹⁴ + x ¹¹ + x ¹⁰ + x ⁹ + x ⁷ + x ⁵ + x ³ + x ¹ + 1
(0x14EAB), start value 0xFFFF). The check sum is re-
formed for each cyclic transmission and is only valid
for the duration of this transmission.
Table 68: Opcode of transmission