XML CO527 Anonymous Questions and Answers Keyword Index

This page provides a keyword index to questions and answers. Clicking on a keyword will take you to a page containing all questions and answers for that keyword, grouped by year.

To submit a question, use the anonymous questions page. You may find the keyword index and/or top-level index useful for locating past questions and answers.

Keyword reference for usart

Question 61 (2013):

Submission reference: IN2927

Does the character echo program only echo one character a each poll, or can it echo multiple characters?

Answer 61:

It deals with a single character (8-bit ASCII byte) at a time. In slide 31 of lecture 9 the character being echo'd is stored in r16 — an 8-bit register, so it can only be a single character. Only at the end of the program does it loop for the next character. This of course means that if flow control is disabled, data will potentially be lost should the program not react fast enough (not a problem here, assuming a 38000 baud serial line vs. a 16 MHz processor).

Keywords: avr , usart

Question 60 (2013):

Submission reference: IN2926

How do you control the USART with polling?

Answer 60:

See lecture 9 and echo38k.asm on Moodle/raptor.

Keywords: avr , usart