MK50H27 Datasheet, PDF (14/56 Pages) STMicroelectronics – Signalling System 7 Link Controller

MK50H27
SECTION 4
PROGRAMMING SPECIFICATION
This section defines the Control and Status Reg-
isters and the memory data structures required to
program the MK50H27.
4.1 Control and Status Registers
There are six Control and Status Registers
(CSR’s) resident within the MK50H27. The
CSR’s are accessed through two bus address-
able ports, an address port (RAP), and a data
port (RDP), thus requiring only two locations in
the system memory or I/O map.
4.1.1 Accessingthe Control & Status Registers
The CSR’s are read (or written) in a two step op-
eration. The address of the CSR is written into the
address port (RAP) during a bus slave transac-
tion. During a subsequent bus slave transaction,
the data being read from (or written into) the data
port (RDP) is read from (or written into) the CSR
selected in the RAP. Once written, the address in
RAP remains unchanged until rewritten or upon a
bus reset. A control I/O pin (ADR) is provided to
distinguish the address port from the data port.
ADR
L
H
Port
Register Data Port (RDP)
Register Address Port (RAP)
4.1.1.1 Register Address Port (RAP)
1111110000000000
5432109876543210
H
B
CSR
B
0 0 0 0 0 0 0 0 M0 0 0
8
<2:0>
Y
T
E
BIT
15:08
07
06:04
03:01
00
NAME
RESERVED
BM8
RESERVED
CS3<2:0>
HBYTE
DESCRIPTION
Must be written as zeroes
When set, places chip into 8 bit mode. CSR’s, Init Block, and data transfers are all 8 bit
transfers; this provides compatibility with 8 bitmicroprocessors. When clear, all transfers
are 16 bit transfers. This bit must be set to the same value each time it is written,
changing this bit during normal operation will achieve unexpected results. BM8 is
READ/WRITE and cleared on Bus RESET.
Must be written as zeroes
CSR address select bits. READ/WRITE. Selects the CSR to be accessed through the
RDP. RAP is cleared by Bus RESET.
CSR<2:0> CSR
0
CSR0
1
CSR1
2
CSR2
3
CSR3
4
CSR4
5
CSR5
Determines which byte is addressed for 8 bit mode. If set, the high byte of the register
referred to by CSR<2:0> is addressed, otherwise the low byte is addressed. This bit is
only meaningful in 8 bit mode and must be written as zero if BM8=0. HBYTE is
READ/WRITE and cleared on bus reset.
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