版本 04fbe6f878ee4fba475b5847a1a5580518e96bdf

embedded/SPI

Changes from 04fbe6f878ee4fba475b5847a1a5580518e96bdf to 7718f7494890b36f492053b32eef240b5b94c176

---
title: SPI
...


Overview
========

..
    關聯在哪？舉例。
    圖例

SPI 為資料傳輸協定，有著以下幾點特色：

.. benfit is what?

- 同步式 
- 全雙工
    - 可以半雙工或單工
- 主從式
    - dynamic change of master/ slave
    - 多個 master
- 8 master baud rate prescalers
- slave mode frequency
- SPI TI / motorola mode 
- MSB-first or LSB-first
- Hardware CRC
- DMA capability
.. BIDI mode / RXONLY (p. 801)
..
    I2S feature
..  I2S feature

Device overview
===============

.. image:: /embedded/SPI/STM32F40x block diagram.png
STM32F40x block diagram [#]_

.. [#] `STM32F405xx, STM32F407xx , STM32F415xx and ... <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf>`_ p.
.. [#] `DS8626: ARM Cortex-M4 32b MCU+FPU, 210DMIPS, up to 1MB Flash/192+4KB RAM, USB OTG HS/FS, Ethernet, 17 TIMs, 3 ADCs, 15 comm. interfaces & camera <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/DM00037051.pdf>`_ p.18

- 3 SPI
  - SPI1: 37.5 Mbits/s
  - SPI2 & SPI3: 21 Mbits/s

.. Datasheet: p.32

SPI functional description
==========================

general
-------
.. 介紹 pin

.. image:: /embedded/SPI/SPI block diagram.png
SPI block diagram [#]_

.. [#] `STM32F405xx, STM32F407xx , STM32F415xx and ... <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf>`_ p.793

- MISO: Master In / Slave Out data
- MISO: Master Out / Slave In data
- SCK: Serial Clock ( Master -> Slave )
- NSS: *(optional)* select slave, low-driven

Clock phase and clock polarity
------------------------------
.. image:: /embedded/SPI/single master _ single slave application.png
SPI single master/single slave application [#]_

.. [#] `STM32F405xx, STM32F407xx , STM32F415xx and ... <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf>`_ p.794

.. baud rate ref menual p.834

..
    Register
    ========
    MSTR: Master selection
    SSOE: SS output enable
    SSM: software SS management
    Slave select(NSS) pin management
    ''''''''''''''''''''''''''''''''

|SPI single master/single slave application|

.. |SPI single master/single slave application| image:: /embedded/SPI/SPI 1-1 application.png
Clock phase and clock polarity
''''''''''''''''''''''''''''''

.. image:: /embedded/SPI/SPI Dota clock timing diagram.png
Data clock timing diagram[#]_

.. [#] `STM32F405xx, STM32F407xx , STM32F415xx and ... <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf>`_ p.796

SPI_PR1 中有兩個 bits CPOL 和 CPHA 控制取值的時間關係，

STM32F4XX 
=========
It has up to 3 SPIs (37.5 Mbits/s), 2 with muxed full-duplex I2S to achieve audio class 
accuracy via internal audio PLL or external clock
- CPOL(clock polarity) 決定閒置時 clock 的電位，CPOL = 0 表閒置時為低電位。
- CPHA(clock phase) 決定在 clock 的哪個 edge 取值， CPHA = 0 表示在第一個 edge (到不同電位時)取值。

SPI1 can communicate at up to 37.5 Mbits/s, SPI2 and SPI3 can communicate at up to 21 Mbit/s.
Data format
'''''''''''

Operation
=========
Data transmission
-----------------
Clock polarity and phase
~~~~~~~~~~~~~~~~~~~~~~~~
Mode numbers
~~~~~~~~~~~~~
..
    may know used structure
    guess: interrupt
Independent slave SPI configuration
-----------------------------------
Daisy chain SPI configuration
------------------------------
Valid SPI communication
-----------------------
interrupts
----------
Example of bit-banging the SPI master protocol
===============================================
- LSB-first or MSB first
- 一次傳送的資料量為 8-bit 或 16-bit

confiurataion in master mode
-------------------------------

confiurataion in slave mode
-------------------------------

half-duplex communication
--------------------------

- BIDMODE 判斷是否為全雙工
- RXONLY 判斷半雙工時為傳送端或接收端。

SPI 可以只做半雙工，在半雙工時，沒用到的另一隻 pin 可作為一般的 GPIO 使用。

.. RXONLY 在 BIDMODE 時有作用否？

data transmission and reception procedures
------------------------------------------

CRC calculation
---------------

Status flag
-----------

Disabling SPI
-------------

Code section
============


Reference
=========
- `Serial Peripheral Interface Bus - Wikipedia, the free encyclopedia <http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus>`_
- Reference manual: `STM32F405xx, STM32F407xx , STM32F415xx and ... <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf>`_
- Datasheet: `DS8626: ARM Cortex-M4 32b MCU+FPU, 210DMIPS, up to 1MB Flash/192+4KB RAM, USB OTG HS/FS, Ethernet, 17 TIMs, 3 ADCs, 15 comm. interfaces & camera <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/DM00037051.pdf>`_

.. need improve

.. _`Reference manual`: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf