Module Operation
1262
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
FlexRay Module
26.2.13.1.2 Data Partition
The data partition of the message RAM stores the data sections of the message buffers configured for
reception / transmission as defined in the header partition. The number of data bytes for each message
buffer can vary from 0 to 254. In order to optimize the data transfer between the shift registers of the two
FlexRay protocol controllers and the message RAM as well as between the host interface and the
message RAM, the physical width of the message RAM is word wise (4 bytes).
The data partition starts right after the last word of the header partition. When configuring the message
buffers in the message RAM the programmer has to assure that the data pointers point to addresses
within the data partition.
shows an example how the payload of the configured message buffers can be stored in the
data partition of the message RAM. Message buffers 0 to 2 are static buffers with a payload of 3, whereas
message buffers 3 to n are dynamic buffers with variable payload.
The beginning of a message buffer’s data section is determined by the data pointer and the payload
length configured in the message buffer’s header section. This enables a flexible usage of the available
RAM space for storage of message buffers with different data lengths.
The storage of the payload data is word aligned. If the size of a message buffer payload is an odd number
of 2-byte words, the remaining 16 bits in the last 32-bit word are unused (see
Figure 26-25. Example Structure of Data Partition in Message RAM
Bit /
Word
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
9
8
7
6
5
4
3
2
1
0
:
MB0 Data3
MB0 Data2
MB0 Data1
MB0 Data0
:
unused
unused
MB0 Data5
MB0 Data4
:
MB1 Data3
MB1 Data2
MB1 Data1
MB1 Data0
:
unused
unused
MB1 Data5
MB1 Data4
:
MB2 Data3
MB2 Data2
MB2 Data1
MB2 Data0
:
unused
unused
MB2 Data5
MB2 Data4
:
MB3 Data3
MB3 Data2
MB3 Data1
MB3 Data0
:
º
º
º
º
:
MB3 Data(k)
MB3 Data(k-1)
MB3 Data(k-2)
MB3 Data(k-3)
:
MBn Data3
MBn Data2
MBn Data1
MBn Data0
:
º
º
º
º
:
º
º
º
º
:
MBn Data(m)
MBn Data(m-1)
MBn Data(m-2)
MBn Data(m-3)
:
unused
unused
unused
unused
:
unused
unused
unused
unused
2046
unused
unused
unused
unused
2047
unused
unused
unused
unused
26.2.13.2 ECC Check
In order to assure the integrity of the data stored in the different RAM blocks of the module (message
RAM, 2 transient buffer RAMs, 2 input buffer RAMs, 2 output buffer RAMs, Transfer Configuration RAM),
the FlexRay module RAMs are optionally ECC protected.
The ECC protection is switched off by default and ECC protection is activated by writing a 4 bit key to the
dedicated ECC lock bits (PEL(3-0)) in the Global Control Register (GCS/R) of the Transfer Unit register
frame. ECC single-bit error correction is enabled by default and can be disabled by the 4-bit key bits SBEL
in the ECC Control Register (ECC_CTRL). Only the Transfer Configuration RAM has the exceptional
functionality that ECC protection can either be switched on or off by PEL(3-0). By default the ECC
protection is switched off and the TCR is not protected.
shows the ECC structure concerning enabling/disabling and error indication.