Infineon Technologies TLE5012B - Writing process to avoid overwriting

TLE5012B
SSC Registers
User’s Manual 69 Rev. 1.2, 2018-02
Writing process to avoid overwritting
When writing in a certain field of a register, it is important to not overwrite the bits from the other fields in the same
register. Therefore -for the registers with many fields- a read has to be done previous to a write, so the content of
the bits from the register can be written back and avoid unintended overwriting in other fields than the desired field.
After a write is recommended to do a read to ensure that the values are correctly set. Figure 6-7 shows the
described sequence when a configuration parameter needs to be changed.
Figure 6-7 SSC data transfer sequence to change a configuration parameter
In the following example the Incremental Interface resolution of a TLE5012B E1000 derivate will be changed from
the default 0.088° (IFAB_RES bits 00
B
in the MOD_4 register) to 0.352° (IFAB_RES bits 10
B
) via a SSC data
tranfer. First, the whole MOD_4 register is read. The bits will be copied in the write word and only the two
IFAB_RES bits changed to the desired configuration. Finally a read confirms that the desired bits have changed
and the rest of the bits remain as they were.
Figure 6-8 Example of a SSC data transfer sequence to change a configuration parameter
readregister
changedesired
bitsonly
writeregister
readregister
(forcheck)
R
MSB LSB MSB LSB MSB LSB
1101000011100001 01001000001000001111111011110100
W
MSB LSB MSB LSB MSB LSB
01010000111000010100100000110000 1111111001100011
R
MSB LSB MSB LSB MSB LSB
1101000011100001 01001000001100001111111001000000
D0E1
H
4830
H
FE40
H
LOCK A DDR ND TCO_X_T
HSM_PL
P
RES MD STA T RESP CRC
…
(t
wr_delay
)
COMMAND READ Data 1 SAFETY-WORD
RES MD STA T RESP CRC
…
(t
wr_delay
)
LOCK A DDR ND TCO_X_T
HSM_PL
P
4830
H
FE63
H
50E1
H
COMMAND WRITE Data 1 SAFETY-WORD
TCO_X_T
HSM_PL
P
MDRES
COMMAND READ Data 1 SAFETY-WORD
…
(t
wr_delay
)
LOCK A DDR ND STA T RESP CRC
D0E1
H
4820
H
FEF4
H