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cpu/esp32: doc update for periph_can

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Gunar Schorcht 2019-08-09 17:24:35 +02:00 committed by Schorcht
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cpu/esp32/doc.txt
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@ -109,7 +109,6 @@ The following table gives a short reference in alphabetical order of modules th
Module | Default | Short description
----------|----------|-------------------
[esp_can](#esp32_can_interfaces) | not used | enable the CAN device
[esp_eth](#esp32_ethernet_network_interface) | not used | enable the Ethernet MAC (EMAC) network device
[esp_gdb](#esp32_debugging) | not used | enable the compilation with debug information for debugging
[esp_hw_counter](#esp32_timers) | not used | use hardware counters for RIOT timers
@ -392,7 +391,6 @@ Optional features of ESP32 can be enabled by ```USEMODULE``` definitions in the
Module | Description
-------|------------
esp_can | Enable the CAN device, see section [CAN Interfaces](#esp32_can_interfaces).
esp_eth | Enable the Ethernet MAC (EMAC) interface as `netdev` network device, see section [Ethernet Network Interface](#esp32_ethernet_network_interface).
esp_gdb | Enable the compilation with debug information for debugging with [QEMU and GDB](#esp32_qemu_mode_and_gdb) (```QEMU=1```) or via [JTAG interface with OpenOCD](#esp32_jtag_debugging).
esp_i2c_hw | Use the hardware I2C implementation, see section [I2C Interfaces](#esp32_i2c_interfaces).
@ -797,7 +795,9 @@ Example:
\anchor esp32_can_interfaces
## <a name="esp32_can_interfaces"> CAN Interfaces </a> &nbsp;[[TOC](#esp32_toc)]
The ESP32 intregates a CAN controller which is compatible with the NXP SJA1000 CAN controller. Thus, it is CAN 2.0B specification compliant and supports two message formats:
The ESP32 intregates a CAN controller which is compatible with the NXP SJA1000
CAN controller. Thus, it is CAN 2.0B specification compliant and supports two
message formats:
- Base Frame Format (11-bit ID)
- Extended Frame Format (29-bit ID)
@ -806,21 +806,34 @@ The ESP32 intregates a CAN controller which is compatible with the NXP SJA1000 C
- ESP32 CAN does not support CAN-FD and is not CAN-FD tolerant.
- ESP32 CAN does not support SJA1000's sleep mode and wake-up functionality.
As with the SJA1000, the ESP32 CAN controller provides only the data link layer and physical layer signaling sublayer. Therefore, depending on the physical layer requirements, an external transceiver module is required which converts the CAN-RX and CAN-TX signals of the ESP32 into CAN_H and CAN_L bus signals, e.g., the MCP2551 or SN65HVD23X transceiver for compatibility with ISO 11898-2.
As with the SJA1000, the ESP32 CAN controller provides only the data link layer
and the physical layer signaling sublayer. Therefore, depending on physical
layer requirements, an external transceiver module is required which converts
the `CAN-RX` and `CAN-TX` signals of the ESP32 into `CAN_H` and `CAN_L` bus
signals, e.g., the MCP2551 or SN65HVD23X transceiver for compatibility with
ISO 11898-2.
The ```esp_can``` module realizes a low-level CAN driver interface for the ESP32 CAN controller and provides a CAN DLL device that can be used with RIOT's CAN protocol stack. It uses the ESP32 CAN controller in SJA1000 PeliCAN mode. Please refer the [SJA1000 Datasheet](https://www.nxp.com/documents/data_sheet/SJA1000.pdf) for detailed information about the CAN controller and its programming.
If module `periph_can` is used, the low-level CAN driver for the
ESP32 CAN controller is enabled. It provides a CAN DLL device that can be
used with RIOT's CAN protocol stack. It uses the ESP32 CAN controller
in SJA1000 PeliCAN mode. Please refer the
[SJA1000 Datasheet](https://www.nxp.com/documents/data_sheet/SJA1000.pdf)
for detailed information about the CAN controller and its programming.
The pin configuration of the CAN interface is usually defined in board specific peripheral configuration by
The pin configuration of the CAN tranceiver interface is usually defined
in board specific peripheral configuration by
- <b>```CAN_TX```</b>, the GPIO used as TX tranceiver signal, and
- <b>```CAN_RX```</b>, the GPIO used as RX tranceiver signal.
If the pin configuration is not defined, the following default configuration is used which can be overridden by the application, see section [Application-Specific Configurations](#esp32_application_specific_configurations).
If the pin configuration is not defined, the following default configuration
is used which can be overridden by the application, see section
[Application-Specific Configurations](#esp32_application_specific_configurations).
Device |Signal|Pin |Symbol |Remarks
:-----------|:-----|:-------|:--------------|:----------------
CAN | TX | GPIO5 |```CAN_TX``` | optional, can be overridden
CAN | RX | GPIO35 |```CAN_RX``` | optional, can be overridden
:-------|:-----|:-------|:--------------|:----------------
CAN | TX | GPIO5 |`CAN_TX` | optional, can be overridden
CAN | RX | GPIO35 |`CAN_RX` | optional, can be overridden
Example:
```
@ -828,15 +841,14 @@ Example:
#define CAN_RX GPIO9 /* CAN RX tranceiver signal */
```
<b>```CAN_DLL_NUMOF```</b> is not defined by the ```esp_can``` module. It uses the default value of 1. If you have further CAN interfaces, make sure to define the correct value of ```CAN_DLL_NUMOF```.
If the board has an external transceiver module connected to the ESP32 on-board,
module `periph_can` should be provided as feature in board's `Makefile.features`
```
FEATURES_PROVIDED += periph_can # CAN peripheral interface
```
If the board has an external transceiver module connected to the ESP32 on board, the ```esp_can``` module should be enabled by default in board's ```Makefile.dep``` when module ```can``` is used.
```
ifneq (,$(filter can,$(USEMODULE)))
USEMODULE += esp_can
endif
```
Otherwise, the application has to add the ```esp_can``` module in its makefile when needed.
Otherwise, the application has to add the `periph_can` module in its makefile
when needed.
## <a name="esp32_other_peripherals"> Other Peripherals </a> &nbsp;[[TOC](#esp32_toc)]