第十一章 MSP430 的 SPI 模組

1. 第十一章MSP430的SPI模組

2. USCI簡介

3. SPI • The Serial Peripheral Interface Bus or SPI (pronounced as either ess-pee-eye or spy) bus is a synchronous serial data link standard, named by Motorola, that operates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select (chip select) lines. Sometimes SPI is called a four-wire serial bus, contrasting with three-, two-, and one-wire serial buses. SPI is often referred to as SSI (Synchronous Serial Interface). -from Wiki http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

4. SPI-Interface • The SPI bus specifies four logic signals: • SCLK: serial clock (output from master); • MOSI: master output, slave input (output from master); • MISO: master input, slave output (output from slave); • SS: slave select (active low, output from master). The SDI/SDO (DI/DO, SI/SO) convention requires that SDO on the master be connected to SDI on the slave, and vice-versa. Chip select polarity is rarely active high, although some notations (such as SS or CS instead of nSS or nCS) suggest otherwise. -from Wiki http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

5. SPI in MSP430 SPI Mode

6. SPI in MSP430 Clock polarity and phase http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

7. SPI in MSP430

8. SPI01_MASTER.C • 以示波器觀察CLK及SIMO訊號變化 CLK SIMO • MSB-first

9. SPI01_MASTER.C • 0x01 • 0x03 • 0x05 • 0x50 • 0x80 CLK Why?? SIMO

10. SPI01_SLAVE.C • 由slave接收資料 • 兩個人一組，一位執行SPI01_MASTER發送資料，另一位執行SPI01_SLAVE接收資料觀察UCA0RXBUF的值 SPI01_MASTER SIMO- SOMI- CLK- GND- SPI01_SLAVE -SIMO -SOMI -CLK -GND • 上述哪一條線可拿掉而不影響結果??Why?

11. SPI02_MASTER.C • 兩個人一組，一位執行SPI02_MASTER發送資料，另一位執行SPI02_SLAVE接收資料，個別觀察UCA0RXBUF的值 SPI01_MASTER SIMO- SOMI- CLK- GND- SPI01_SLAVE -SIMO -SOMI -CLK -GND

12. SPI02_SLAVE.C CLK SIMO SOMI • Synchronous • 請參考上圖訊號，思考SPI傳輸特性。 資料傳輸時，何者主動?何者被動?

13. SPI03_MASTER.C • 中斷 • 兩個人一組，一位執行SPI03_MASTER發送資料，另一位執行SPI03_SLAVE接收資料，設定中斷，個別觀察UCA0RXBUF的值 SPI01_MASTER SIMO- SOMI- CLK- GND- SPI01_SLAVE -SIMO -SOMI -CLK -GND

14. SPI03_SLAVE.C • 試拔除所有連線，觀察MASTER端傳資料出去後是否仍會進入RX中斷? 為什麼?

15. SPI04_MASTER.C • 中斷 • 兩個人一組，一位執行SPI04_MASTER發送資料，另一位執行SPI04_SLAVE接收資料， SPI04_SLAVE 先執行，觀察兩端閃燈狀況。 SPI01_MASTER SIMO- SOMI- CLK- GND- SPI01_SLAVE -SIMO -SOMI -CLK -GND

16. SPI04_SLAVE.C • 為何MASTER端總是比SLAVE端慢一次?

17. SPI05_MASTER.C • 讀取sensor值 • 兩個人一組，一位執行SPI05_MASTER發送資料，另一位執行SPI05_SLAVE接收資料， SPI05_SLAVE 先執行，觀察MASTER端收到的值。 SPI01_MASTER SIMO- SOMI- CLK- GND- SPI01_SLAVE -SIMO -SOMI -CLK -GND • 試想，Master端要讀Slave的值，為何需要傳資料給Slave??

18. SPI05_SLAVE.C • 試將紅框那一行移除，重新執行上述步驟，會有甚麼差異?