docs: Add a section to the FAQ on translating Marlin pin numbers

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
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Kevin O'Connor 2018-08-24 21:36:37 -04:00
parent 11e9bb286e
commit a27e82aef3
1 changed files with 50 additions and 1 deletions

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@ -14,7 +14,8 @@ Frequently asked questions
11. [My TMC motor driver turns off in the middle of a print](#my-tmc-motor-driver-turns-off-in-the-middle-of-a-print) 11. [My TMC motor driver turns off in the middle of a print](#my-tmc-motor-driver-turns-off-in-the-middle-of-a-print)
12. [When I set "restart_method=command" my AVR device just hangs on a restart](#when-i-set-restart_methodcommand-my-avr-device-just-hangs-on-a-restart) 12. [When I set "restart_method=command" my AVR device just hangs on a restart](#when-i-set-restart_methodcommand-my-avr-device-just-hangs-on-a-restart)
13. [Will the heaters be left on if the Raspberry Pi crashes?](#will-the-heaters-be-left-on-if-the-raspberry-pi-crashes) 13. [Will the heaters be left on if the Raspberry Pi crashes?](#will-the-heaters-be-left-on-if-the-raspberry-pi-crashes)
14. [How do I upgrade to the latest software?](#how-do-i-upgrade-to-the-latest-software) 14. [How do I convert a Marlin pin number to a Klipper pin name?](#how-do-i-convert-a-marlin-pin-number-to-a-klipper-pin-name)
15. [How do I upgrade to the latest software?](#how-do-i-upgrade-to-the-latest-software)
### How can I donate to the project? ### How can I donate to the project?
@ -263,6 +264,54 @@ heaters and temperature sensors are functioning correctly. See the
[example-extras.cfg](../config/example-extras.cfg) for further [example-extras.cfg](../config/example-extras.cfg) for further
details. details.
### How do I convert a Marlin pin number to a Klipper pin name?
Short answer: There isn't an easy way to do that reliably. In some
cases one can use Klipper's `pin_map: arduino` feature. Otherwise, for
"digital" pins, one method is to search for the requested pin in
Marlin's fastio header files. The Atmega2560 and Atmega1280 chips use
[fastio_1280.h](https://github.com/MarlinFirmware/Marlin/blob/1.1.9/Marlin/fastio_1280.h),
while the Atmega644p and Atmega1284p chips use
[fastio_644.h](https://github.com/MarlinFirmware/Marlin/blob/1.1.9/Marlin/fastio_644.h).
For example, if you are looking to translate Marlin's digital pin
number 23 on an atmega2560 then one could find the following line in
Marlin's fastio_1280.h file:
```
#define DIO23_PIN PINA1
```
The `DIO23` indicates the line is for Marlin's pin 23 and the `PINA1`
indicates the pin uses the hardware name of `PA1`. Klipper uses the
hardware names (eg, `PA1`).
Long answer: Klipper uses the standard pin names defined by the
micro-controller. On the Atmega chips these hardware pins have names
like `PA4`, `PC7`, or `PD2`.
Long ago, the Arduino project decided to avoid using the standard
hardware names in favor of pin names based on incrementing numbers -
these Arduino names generally look like `D23` or `A14`. This was an
unfortunate choice that has lead to great deal of confusion. In
particular the Arduino pin numbers frequently don't translate to the
same hardware names. For example, `D21` is `PD0` on one common Arduino
board, but is `PC7` on another common Arduino board.
In order to support 3d printers based on real Arduino boards, Klipper
supports the Arduino pin aliases. This feature is enabled by adding
`pin_map: arduino` to the [mcu] section of the config file. When these
aliases are enabled, Klipper understands pin names that start with the
prefix "ar" (eg, Arduino pin `D23` is Klipper alias `ar23`) and the
prefix "analog" (eg, Arduino pin `A14` is Klipper alias `analog14`).
Klipper does not use the Arduino names directly because we feel a name
like D7 is too easily confused with the hardware name PD7.
Marlin primarily follows the Arduino pin numbering scheme. However,
Marlin supports a few chips that Arduino does not support and in some
cases it supports pins that Arduino boards do not expose. In these
cases, Marlin chose their own pin numbering scheme. Klipper does not
support these custom pin numbers - see the "short answer" section
above for information on translating these pin numbers to their
standard hardware names.
### How do I upgrade to the latest software? ### How do I upgrade to the latest software?
The general way to upgrade is to ssh into the Raspberry Pi and run: The general way to upgrade is to ssh into the Raspberry Pi and run: