ST90158 - MIRROR REGISTER (MR)
9.7 MIRROR REGISTER (MR)
9.7.1 Introduction
The Mirror Register transforms the bit order of a
byte from Most Significant Bit first (MSB-first) to
Least Significant Bit first (LSB-first) or vice versa.
This feature can be used, for example, when pro-
gramming the SCI (which transfers data MSB-first)
to emulate an SPI device (which transfers data
LSB-first).
Expressed in hexadecimal notation, for example:
– If you write 0F0h, you will read 00Fh
– If you write 0AAh, you will read 055h
– If you write 03Ch you will read 03Ch
9.7.4 Register Description
9.7.2 Main Features
MIRROR REGISTER (MIRROR)
R241 - Read/Write
Register Page: 0
■ Single 8-bit register address
■ Hardware mirroring
Reset Value: 0000 0000 (00h)
9.7.3 General Description
7
0
The operation of the MIRROR register can be de-
scribed as follows:
MIR7 MIR6 MIR5 MIR4 MIR3 MIR2 MIR1 MIR0
If software writes the 8-bit binary value:
Bit 7:0 = MIR[7:0] Mirror register bits.
mnopqrst
a subsequent read access to the MIRROR register
address will return:
tsrqponm
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ETC [ ETC ]
