UART Driver - Revision history

Michael: /* Initialization */

2008-09-11T23:54:22Z

Initialization

2008-02-14T21:14:50Z

Initialization: Added formula to determine divisor

2007-08-02T19:27:13Z

Added warning about no interrupts while in loopback

2007-08-02T18:20:04Z

Loopback

2007-08-02T18:19:38Z

Loopback

2007-08-02T18:19:02Z

Control

2007-07-31T17:13:36Z

Removed circular link under "See also"

2007-07-11T21:49:02Z

2007-07-11T20:18:41Z

2007-07-11T20:13:17Z

@@ Line 17: / Line 17: @@
 Where <tt>baud_rate</tt> is the speed you wish to connect at (typically 115,200) and
 :<math>baud\_base=\frac{clockrate}{16}</math>.
-The clockrate should be measured in hertz and may not be equivalent to the clockspeed.  (The [[WRT54GL]], for example, has a hard-coded clockrate of 20,000,000 or 20MHz.)
+The clockrate should be measured in hertz and may not be equivalent to the clockspeed.  (The [[WRT54GL]], for example, has a hard-coded clockrate of 20,000,000 or 20MHz, while the [[WRT54G]] has a clockrate of about 25MHz.)
 == Upper Half (Read and Write) ==

@@ Line 8: / Line 8: @@
 == Initialization ==
-Intialize defines the starting values for all members of the control block: statistical counts are zeroed, buffers are defined, and semaphores are allocated.  Also part of the intialization process is setting values in the control and status registers:
+Intialize defines the starting values for all members of the control block: statistical counts are zeroed, buffers are defined, and semaphores are allocated.  Also part of the initialization process is setting values in the control and status registers:
 * Line control is set to 8 bit, no parity, 1 stop.
 * Receiver FIFO full, transmitt buffer empty, and receiver line status interrupts are enabled.
 * Hardware FIFOs are enabled.
 == Upper Half (Read and Write) ==

@@ Line 29: / Line 29: @@
 === Loopback ===
-<code>UART_ENABLE_LOOPBACK</code> and <code>UART_DISABLE_LOOPBACK</code> control functions enable and disable hardware loopback.  Be aware that loopback is precarious and must be used carefully.  Prior to enabling and disabling hardware loopback, the control function ensures the transmitter is completely empty and has completed all previous transmission.  It is recommended that you turn off interrupts prior to enabling loopback and after disabling loopback to avoid interleaving output while in loopback mode.
+<code>UART_ENABLE_LOOPBACK</code> and <code>UART_DISABLE_LOOPBACK</code> control functions enable and disable hardware loopback.  Be aware that loopback is precarious and must be used carefully.  It is recommended that you turn off interrupts prior to enabling loopback and after disabling loopback to avoid interleaving output while in loopback mode.
 == See also ==
 * [[TTY Driver]]

@@ Line 29: / Line 29: @@
 === Loopback ===
-<code>UART_ENABLE_LOOPBACK</code> and <code>UART_DISABLE_LOOPBACK</code> control functions enable and disable hardware loopback.  Beware that loopback is precarious and must be used carefully.  Prior to enabling and disabling hardware loopback, the control function ensures the transmitter is completely empty and has completed all previous transmission.  It is recommended that you turn off interrupts prior to enabling loopback and after disabling loopback to avoid interleaving output while in loopback mode.
+<code>UART_ENABLE_LOOPBACK</code> and <code>UART_DISABLE_LOOPBACK</code> control functions enable and disable hardware loopback.  Be aware that loopback is precarious and must be used carefully.  Prior to enabling and disabling hardware loopback, the control function ensures the transmitter is completely empty and has completed all previous transmission.  It is recommended that you turn off interrupts prior to enabling loopback and after disabling loopback to avoid interleaving output while in loopback mode.
 == See also ==
 * [[TTY Driver]]

@@ Line 29: / Line 29: @@
 === Loopback ===
-<code>UART_ENABLE_LOOPBACK</code> and <code>UART_DISABLE_LOOPBACK</code> control functions enable and disable hardware loopback.  Prior to enabling and disabling hardware loopback, the control function ensures the transmitter is completely empty and has completed all previous transmission.  It is recommended that you turn off interrupts prior to enabling loopback and after disabling loopback to avoid interleaving output while in loopback mode.
+<code>UART_ENABLE_LOOPBACK</code> and <code>UART_DISABLE_LOOPBACK</code> control functions enable and disable hardware loopback.  Beware that loopback is precarious and must be used carefully.  Prior to enabling and disabling hardware loopback, the control function ensures the transmitter is completely empty and has completed all previous transmission.  It is recommended that you turn off interrupts prior to enabling loopback and after disabling loopback to avoid interleaving output while in loopback mode.
 == See also ==
 * [[TTY Driver]]

@@ Line 27: / Line 27: @@
 == Control ==
 The control functions are used to set, clear, and get the input and output flags for the UART driver.  Non-blocking flags indicate the upper half read and write functions should perform as much of the requested read or write length as possible, but should not block to wait for the lower half to fill or empty the input or output buffers.  When the echo input flag is set, the UART outputs every byte as it is received in addition to placing the byte in the input buffer.
 == See also ==
 * [[TTY Driver]]

← Older revision		Revision as of 17:13, 31 July 2007
Line 29:		Line 29:

	== See also ==		== See also ==
−	* [[National Semiconductor 16550 UART]]
	* [[TTY Driver]]		* [[TTY Driver]]

@@ Line 5: / Line 5: @@
 == Physical UART ==
+The XINU backends have been equipped with serial ports that are representative of the National Semiconductor 16550 UART.  Documentation on the 16550 UART can be found at [http://www.national.com/ds.cgi/NS/NS16C552.pdf http://www.national.com/ds.cgi/NS/NS16C552.pdf].
 == Initialization ==

← Older revision		Revision as of 20:18, 11 July 2007
Line 1:		Line 1:
−	[[Image:UartAsyncDriver.png\|~~frame~~\|~~UART Driver Structure~~]]	+	[[Image:UartAsyncDriver.png\|right\|450px]]
	The UART driver is a char-oriented driver designed to work with a [[National Semiconductor 16550 UART]]. The driver is responsible for receiving and sending bytes of data asynchronously.		The UART driver is a char-oriented driver designed to work with a [[National Semiconductor 16550 UART]]. The driver is responsible for receiving and sending bytes of data asynchronously.

@@ Line 14: / Line 14: @@
 * Hardware FIFOs are enabled.
-== Upper Half (Read and Write) ===
+== Upper Half (Read and Write) ==
 Read is part of the upper half of the driver that fills a user supplied buffer with bytes from the input buffer filled by the lower half of the driver.  If the input buffer is empty, read waits for the lower half to signal on the input semaphore and indicate bytes are avaiable in the input buffer.