MirrorSave
/
nodemcu-firmware
mirror of https://github.com/nodemcu/nodemcu-firmware.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Document HSPI pin functions (#1790)

This commit is contained in:
Arnim Läuger 2017-02-10 21:48:32 +01:00 committed by Marcel Stör
parent 00bc9403fe
commit 4dbf979cb4
1 changed files with 20 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
docs/en/modules/spi.md
View File

@ -10,6 +10,17 @@ For technical details of the underlying hardware refer to [metalphreak's ESP8266
The ESP hardware provides two SPI busses, with IDs 0, and 1, which map to pins generally labelled SPI and HSPI. If you are using any kind of development board which provides flash, then bus ID 0 (SPI) is almost certainly used for communicating with the flash chip. You probably want to choose bus ID 1 (HSPI) for your communication, as you will have uncontended use of it. The ESP hardware provides two SPI busses, with IDs 0, and 1, which map to pins generally labelled SPI and HSPI. If you are using any kind of development board which provides flash, then bus ID 0 (SPI) is almost certainly used for communicating with the flash chip. You probably want to choose bus ID 1 (HSPI) for your communication, as you will have uncontended use of it.
HSPI signals are fixed to the following IO indices and GPIO pins:
| Signal | IO index | ESP8266 pin |
|-----------|----------|-------------|
| HSPI CLK | 5 | GPIO14 |
| HSPI /CS | 8 | GPIO15 |
| HSPI MOSI | 7 | GPIO13 |
| HSPI MISO | 6 | GPIO12 |
See also [spi.setup()](#spisetup).
## High Level Functions ## High Level Functions
The high level functions provide a send & receive API for half- and The high level functions provide a send & receive API for half- and
full-duplex mode. Sent and received data items are restricted to 1 - 32 bit full-duplex mode. Sent and received data items are restricted to 1 - 32 bit
@ -86,6 +97,8 @@ _, _, x = spi.send(1, 0, {255, 255, 255})
Set up the SPI configuration. Set up the SPI configuration.
Refer to [Serial Peripheral Interface Bus](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Clock_polarity_and_phase) for details regarding the clock polarity and phase definition. Refer to [Serial Peripheral Interface Bus](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Clock_polarity_and_phase) for details regarding the clock polarity and phase definition.
Calling `spi.setup()` will route the HSPI signals to the related pins, overriding previous configuration and control by the `gpio` module. It is possible to revert any pin back to gpio control if its HSPI functionality is not needed, just set the desired `gpio.mode()` for it. This is recommended especially for the HSPI /CS pin function in case that SPI slave-select is driven from a different pin by `gpio.write()` - the SPI engine would toggle pin 8 otherwise.
#### Syntax #### Syntax
`spi.setup(id, mode, cpol, cpha, databits, clock_div[, duplex_mode])` `spi.setup(id, mode, cpol, cpha, databits, clock_div[, duplex_mode])`
@ -109,6 +122,13 @@ Refer to [Serial Peripheral Interface Bus](https://en.wikipedia.org/wiki/Serial_
#### Returns #### Returns
Number: 1 Number: 1
#### Example
```lua
spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, 8, 8)
-- we won't be using the HSPI /CS line, so disable it again
gpio.mode(8, gpio.INPUT, gpio.PULLUP)
```
## Low Level Hardware Functions ## Low Level Hardware Functions
The low level functions provide a hardware-centric API for application The low level functions provide a hardware-centric API for application
scenarios that need to excercise more complex SPI transactions. The scenarios that need to excercise more complex SPI transactions. The