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SAMA5 CAN: Update readme on how to configure CAN

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Gregory Nutt
2013-10-23 11:32:12 -06:00
parent c0bbb8ee01
commit 5edb122b87
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configs/sama5d3x-ek/README.txt
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@@ -77,6 +77,7 @@ Contents
- HSMCI Card Slots - HSMCI Card Slots
- USB Ports - USB Ports
- AT24 Serial EEPROM - AT24 Serial EEPROM
- CAN Usage
- SAMA5D3x-EK Configuration Options - SAMA5D3x-EK Configuration Options
- Configurations - Configurations
@@ -652,6 +653,85 @@ AT24 Serial EEPROM
By default, PA30 and PA31 are SWJ-DP pins, it can be used as a pin for TWI By default, PA30 and PA31 are SWJ-DP pins, it can be used as a pin for TWI
peripheral in the end application. peripheral in the end application.
CAN Usage
=========
CAN Configuration
-----------------
The following steps illustrate how to enable CAN0 and/or CAN1 in the NuttX
configuration:
System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_CAN0=y : Select CAN0 and/or CAN1
CONFIG_SAMA5_CAN1=y
Device Drivers -> CAN Driver Support
CONFIG_CAN=y : (Automatically selected)
CONFIG_CAN_EXTID=y : For extended, 29-bit CAN IDs
System Type -> CAN Drive Support
CONFIG_SAMA5_CAN0_BAUD=250000 : Select some BAUD for CAN0 (if enabled)
CONFIG_SAMA5_CAN0_NRECVMB=1 : Select number of receive mailboxes (see below)
CONFIG_SAMA5_CAN1_BAUD=250000 : Select some BAUD for CAN1 (if enabled)
CONFIG_SAMA5_CAN1_NRECVMB=1 : Select number of receive mailboxes (see below)
Receive Mailboxes and Address Filtering
---------------------------------------
The SAMA5 CAN0 peripheral supports 8 mailboxes that can be used for sending
and receiving messages. Note that the number of dedicated receive mailboxes
(CONFIG_SAMA5_CANn_NRECVMB) was set to one in the above configuration. This
could be set to any value from 1 to 3 (the upper limit of 3 is purely
arbrary and can be increased with some minor code enhancement). The
remainder can be configured dynamically to send CAN messages.
Why would you want to use more than one receive mailbox? There are two
reasons. Multiple receive mailboxes might needed to either (1) receive
bursts of messages, or (2) to support multiple groups of messages filtered
on message ID.
You must also specify the address filtering for each dedicated receive mailbox:
System Type -> CAN Drive Support
CONFIG_SAMA5_CAN0_ADDR0 and CONFIG_SAMA5_CAN0_MASK0 : If CONFIG_SAMA5_CAN0_NRECVMB >= 1
CONFIG_SAMA5_CAN0_ADDR1 and CONFIG_SAMA5_CAN0_MASK1 : If CONFIG_SAMA5_CAN0_NRECVMB >= 2
CONFIG_SAMA5_CAN0_ADDR2 and CONFIG_SAMA5_CAN0_MASK2 : If CONFIG_SAMA5_CAN0_NRECVMB >= 3
CONFIG_SAMA5_CAN1_ADDR0 and CONFIG_SAMA5_CAN1_MASK0 : If CONFIG_SAMA5_CAN1_NRECVMB >= 1
CONFIG_SAMA5_CAN1_ADDR1 and CONFIG_SAMA5_CAN1_MASK1 : If CONFIG_SAMA5_CAN1_NRECVMB >= 2
CONFIG_SAMA5_CAN1_ADDR2 and CONFIG_SAMA5_CAN1_MASK2 : If CONFIG_SAMA5_CAN1_NRECVMB >= 3
Only messages that have IDs that match the CONFIG_SAMA5_CANn_ADDRn when both
the received and the configured address are masked by CONFIG_SAMA5_CANn_MASKn
will be accepted. For eacmple, if the mask is all ones, then only messasges
with exact address matches will be accepted; if the mask is all zeroes than
any address will be accepted.
CAN connectors
--------------
CAN1 and CAN2 are available via RJ-11 connectors on the SAMA5Dx-EK. Each
is wired as follows. Also shown below is the matching pins if you want connect
the CAN to a device that uses an DB-9 connector. Both connector types are
common.
+----------+ RJ-11 DB-9
| O | ----------- --------------
+------------+ | | Pin 1 3v3 Pin 1 N/C
| +--+ | | o5 | Pin 2 5v Pin 2 CANL
| | | | | o9 | Pin 3 N/C Pin 3 GND
| +-+ +-+ | | o4 | Pin 4 CANL Pin 4 N/C
| | | | | o8 | Pin 5 CANH Pin 5 N/C
| |654321| | | o3 | Pin 6 N/C Pin 6 N/C
| |oooooo| | | o7 | Pin 7 CANH
| +------+ | | o2 | Pin 8 N/C
+------------+ | o6 | Pin 9 N/C
RJ-11 Female | x1 |
| |
| O |
+----------+
DB-9 Male
SAMA5D3x-EK Configuration Options SAMA5D3x-EK Configuration Options
================================= =================================