aLec25_SCI - Introduction to Embedded Microcomputer Systems...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Introduction to Embedded Microcomputer Systems Lecture 25.1 Jonathan W. Valvano Recap ADC Nyquist Theorem How OC interrupts create a sampling rate Accuracy versus resolution Overview Device driver Serial communication; what does the frame look like SCI shift register versus SCI data register How RDRF is set; how RDRF is cleared How TDRE is set; how TDRE is cleared A device driver is a collection of software functions that allow higher level software to utilize an I/O device. Collection of public methods (subroutines) SCI1_Init SCI1_InChar SCI1_OutChar Collection of private objects (subroutines, globals, I/O ports) SCI1CR2 SCI1BD SCI1SR1 SCI1DRL complexity abstraction divide a complex problem into simple subcomponents functional abstraction divide a problem into modules grouped by function 8.2. Serial Communications Interface, SCI baud rate total number of bits transmitted per second M , selects 8-bit (M=0) or 9-bit (M=1) data frames. A frame is the smallest complete unit of serial transmission. bandwidth useful information transmitted per second. 5V 0V b 0 b 1 b 2 b 3 b 4 b 5 b 6 serial port b 7 one frame start stop Figure 8.1. A serial data frame with M=0. 16 2 6 15 1 3 4 5 11 14 + - + - + - + - + - 13 12 0.2 μ F 0.1 μ F 0.1 μ F 0.1 μ F 0.1 μ F +5V MAX232A TxD RxD PS1 PS0 Ground 9S12DP512 SCI0 EIA-574 Pin 3 Pin 2 Pin 5 DTE TxD RxD SG
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Introduction to Embedded Microcomputer Systems Lecture 25.2 Jonathan W. Valvano TxD 11 14 13 12 MAX232A RxD PS3 PS2 Ground 9S12DP512 SCI1 TxD RxD SG TxD 14 13 12 MAX232A RxD PS3 PS2 Ground 9S12DP512 SCI1 TxD RxD SG Transmitting in asynchronous mode (Lab 7 uses SCI1 ) SCI1DRL write data 10 stop start
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

aLec25_SCI - Introduction to Embedded Microcomputer Systems...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online