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Add support for 20MHz clock source #3

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30a2c02
Added table for 20MHz clock source
bsundahl1 Jun 10, 2023
1572fff
update docs for MCP25625
bsundahl1 Jun 11, 2023
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17 changes: 11 additions & 6 deletions API.md
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ Returns `1` on success, `0` on failure.

### Set pins

#### MCP2515
#### MCP2515 and MCP25625

Override the default `CS` and `INT` pins used by the library. **Must** be called before `CAN.begin(...)`.

Expand All @@ -47,7 +47,7 @@ This call is optional and only needs to be used if you need to change the defaul

### Set SPI Frequency

**MCP2515 only**
**MCP2515 and MCP25625 only**

Override the default SPI frequency of 10 MHz used by the library. **Must** be called before `CAN.begin(...)`.

Expand All @@ -60,16 +60,21 @@ This call is optional and only needs to be used if you need to change the defaul

### Set Clock Frequency

**MCP2515 only**
**MCP2515 and MCP25625 only**

Override the default clock source frequency that is connected to the MCP2515. **Must** be called before `CAN.begin(...)`.

```arduino
CAN.setClockFrequency(clockFrequency);
```
* `clockFrequency` - new clock frequency to use (`8E6`, `16E6`) connected to MCP2515, defaults to `16 Mhz`

This call is optional and only needs to be used if you need to change the clock source frequency connected to the MCP2515. Most shields have a 16 MHz clock source on board, some breakout boards have a 8 MHz source.
* `clockFrequency` - new clock frequency to use (`8E6`, `16E6`, `20E6`)
connected to MCP2515/MCP25625 OSC pins, defaults to `16 Mhz`

This call is optional and only needs to be used if you need to
change the clock source frequency connected to the MCP2515.
Most shields have a 16 MHz clock source on board, some breakout
boards have a 8 MHz source, and some MCP25625 boards use 20 MHz.
If using 20 MHz, the 5E3 bps CAN bitrate is not avilable.

### End

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7 changes: 5 additions & 2 deletions README.md
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Expand Up @@ -6,9 +6,10 @@ An Arduino library for sending and receiving data using CAN bus.

* [Microchip MCP2515](http://www.microchip.com/wwwproducts/en/en010406) based boards/shields
* [Arduino MKR CAN shield](https://store.arduino.cc/arduino-mkr-can-shield)
* Microchip MCP25625 based boards/shields
* [Espressif ESP32](http://espressif.com/en/products/hardware/esp32/overview)'s built-in [SJA1000](https://www.nxp.com/products/analog/interfaces/in-vehicle-network/can-transceiver-and-controllers/stand-alone-can-controller:SJA1000T) compatible CAN controller with an external 3.3V CAN transceiver

### Microchip MCP2515 wiring
### Microchip MCP2515/MCP25625 wiring

| Microchip MCP2515 | Arduino |
| :---------------: | :-----: |
Expand All @@ -23,7 +24,9 @@ An Arduino library for sending and receiving data using CAN bus.

`CS` and `INT` pins can be changed by using `CAN.setPins(cs, irq)`. `INT` pin is optional, it is only needed for receive callback mode. If `INT` pin is used, it **must** be interrupt capable via [`attachInterrupt(...)`](https://www.arduino.cc/en/Reference/AttachInterrupt).

**NOTE**: Logic level converters must be used for boards which operate at 3.3V.
**NOTE**: Logic level converters must be used for boards MCP2515
which operate at 3.3V. The MCP25625 can run on 3.3V or 5V power,
resolving this issue.

### Espressif ESP32 wiring

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18 changes: 18 additions & 0 deletions src/MCP2515.cpp
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Expand Up @@ -88,6 +88,10 @@ int MCP2515Class::begin(long baudRate, bool stayInConfigurationMode)
return 0;
}

if( (baudRate == 5E3) && (_clockFrequency == 20E6) )
// with a 20MHz clock, the minimum baud rate is 6.25kHz
return 0;

const struct {
long clockFrequency;
long baudRate;
Expand Down Expand Up @@ -118,7 +122,21 @@ int MCP2515Class::begin(long baudRate, bool stayInConfigurationMode)
{ (long)16E6, (long)20E3, { 0x0f, 0xff, 0x87 } },
{ (long)16E6, (long)10E3, { 0x1f, 0xff, 0x87 } },
{ (long)16E6, (long)5E3, { 0x3f, 0xff, 0x87 } },

{ (long)20E6, (long)1000E3, { 0x40, 0xd2, 0x82 } }, // 10 Tq, sp 70%, sjw=2, 3 samples (tested)
{ (long)20E6, (long)500E3, { 0x40, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples (tested)
{ (long)20E6, (long)250E3, { 0x41, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples (tested)
{ (long)20E6, (long)200E3, { 0x41, 0xff, 0x87 } }, // 25 Tq, sp 68%, sjw=2, 3 samples
{ (long)20E6, (long)125E3, { 0x43, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples (tested)
{ (long)20E6, (long)100E3, { 0x44, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples
{ (long)20E6, (long)80E3, { 0x44, 0xff, 0x87 } }, // 25 Tq, sp 70%, sjw=2, 3 samples
{ (long)20E6, (long)50E3, { 0x49, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples
{ (long)20E6, (long)40E3, { 0x49, 0xff, 0x87 } }, // 25 Tq, sp 68%, sjw=2, 3 samples
{ (long)20E6, (long)20E3, { 0x58, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples
{ (long)20E6, (long)10E3, { 0x71, 0xf5, 0x85 } }, // 20 Tq, sp 70%, sjw=2, 3 samples
{ (long)20E6, (long)5E3, { 0x7f, 0xff, 0x87 } }, // 6.25kHz is as slow as it can go
};
//https://www.kvaser.com/support/calculators/bit-timing-calculator/ (use MCP2510 option)

const uint8_t* cnf = NULL;

Expand Down