Message Ram; Figure 398. Message Ram Configuration - ST STM32G0 1 Series Reference Manual

RM0444
36.3.3

Message RAM

The Message RAM has a width of 32 bits, and the FDCAN module is configured to allocate
up to 212 words in it. It is not necessary to configure each of the sections shown in
Figure 398.
When the FDCAN addresses the Message RAM, it addresses 32-bit words (aligned), not a
single byte. The RAM address are 32-bit words, i.e. only bits 15 to 2 are evaluated, the two
least significant bits are ignored.
Rx handling
The Rx Handler controls the acceptance filtering, the transfer of received messages to Rx to
one of the two Rx FIFOs, as well as the Rx FIFO Put and Get Indexes.
Acceptance filter
The FDCAN offers the possibility to configure two sets of acceptance filters, one for
standard identifiers and another for extended identifiers. These filters can be assigned to Rx
FIFO 0 or Rx FIFO 1. For acceptance filtering each list of filters is executed from element #0
until the first matching element. Acceptance filtering stops at the first matching element.
Following filter elements are not evaluated for this message.
The main features are:
•
Each filter element can be configured as
–
–
–
•
Each filter element is configurable for acceptance or rejection filtering
• Each filter element can be enabled/disabled individually
•
Filters are checked sequentially, execution stops with the first matching filter element

Figure 398. Message RAM configuration

FLSSA = 0x0000
FLESA = 0x0070
F0SA = 0x00B0
F1SA = 0x188
EFSA = 0x0260
TBSA = 0x0278
0x0350
range filter (from - to)
filter for one or two dedicated IDs
classic bit mask filter
FD controller area network (FDCAN)
11-bit filter
29-bit filter
Rx FIFO 0
Rx FIFO 1
Tx event FIFO
Tx buffers
32 bits
RM0444 Rev 5
28 elements / 28 words
8 elements / 16 words
3 elements / 54 words
3 elements / 54 words
3 elements / 6 words
3 elements / 54 words
MS47278V3
1211/1390
1261