| 0,0 → 1,156 |
|---|
| /* |
| Copyright (C) 2004 John Orlando |
| |
| AVRcam: a small real-time image processing engine. |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public |
| License as published by the Free Software Foundation; either |
| version 2 of the License, or (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public |
| License along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| |
| For more information on the AVRcam, please contact: |
| |
| john@jrobot.net |
| |
| or go to www.jrobot.net for more details regarding the system. |
| */ |
| /*********************************************************** |
| Module Name: UartInterface.c |
| Module Date: 04/10/2004 |
| Module Auth: John Orlando |
| |
| Description: This module is responsible for providing an |
| interface to the UART hardware available on the mega8. |
| This interface is an interrupt-driven interface. |
| |
| Revision History: |
| Date Rel Ver. Notes |
| 4/10/2004 0.1 Module created |
| 6/30/2004 1.0 Initial release for Circuit Cellar |
| contest. |
| 11/15/2004 1.2 Updated UART baud rate regs so that |
| it runs at 115.2 kbps when the input |
| crystal is at 17.7 MHz (which is the |
| speed of the OV6620's crystal). |
| 1/16/2005 1.4 Moved the serial received ISR to |
| this file, instead of having it |
| in its own UartInterfaceAsm.S file |
| written in assembly. |
| ***********************************************************/ |
| |
| /* Includes */ |
| #include <avr/io.h> |
| #include <avr/interrupt.h> |
| #include "CommonDefs.h" |
| #include "UartInterface.h" |
| #include "UIMgr.h" |
| #include "Executive.h" |
| |
| /* Local Variables */ |
| |
| /* Local Structures and Typedefs */ |
| |
| /* Extern Variables */ |
| |
| /* Definitions */ |
| |
| /*********************************************************** |
| Function Name: UartInt_init |
| Function Description: This function is responsible for |
| initializing the UART interface on the mega8. This |
| interface is set to communicate at 115.2 Kbps, with an |
| 8N1 protocol. |
| Inputs: none |
| Outputs: none |
| ***********************************************************/ |
| void UartInt_init(void) |
| { |
| /* set up the baud rate registers so the UART will operate |
| at 115.2 Kbps */ |
| UBRRH = 0x00; |
| |
| #ifdef NO_CRYSTAL |
| UBRRL = 18; /* 18 for double clocking at 115.2 kbps */ |
| #else |
| UBRRL = 0x08; /* for 16 MHz crystal at 115.2 kbps */ |
| #endif |
| |
| /* enable the tx and rx capabilities of the UART...as well |
| as the receive complete interrupt */ |
| UCSRB = (1<<RXCIE)|(1<<RXEN)|(1<<TXEN); |
| |
| /* set up the control registers so the UART works at 8N1 */ |
| UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0); |
| |
| #ifdef NO_CRYSTAL |
| /* set the baud rate to use the double-speed */ |
| UCSRA = (1<<U2X); |
| #endif |
| |
| } |
| |
| /*********************************************************** |
| Function Name: UartInt_txByte |
| Function Description: This function is responsible for |
| transmitting a single byte on the uart. |
| Inputs: txByte - the byte to send |
| Outputs: none |
| NOTES: When the TX UDRE (data register empty) is set, there |
| is puposefully no interrupt...thus, to send a string of |
| data out, the calling routine needs to hold up the entire |
| application while this takes place (or just send one |
| byte at a time at strtegically timed intervals, like |
| the stats data is sent out :-) |
| ***********************************************************/ |
| void UartInt_txByte(unsigned char txByte) |
| { |
| /* Wait for empty transmit buffer */ |
| while ( !( UCSRA & (1<<UDRE)) ); |
| /* Put data into buffer, sends the data */ |
| UDR = txByte; |
| } |
| |
| /*********************************************************** |
| Function Name: SIG_UART_RECV ISR |
| Function Description: This function is responsible for |
| handling the interrupt caused when a data byte is |
| received by the UART. |
| Inputs: none |
| Outputs: none |
| NOTES: This function was originally written in assembly, |
| but moved over to C when the setting of the "T" bit at |
| the end of the routine was no longer necessary (this |
| theoretically allowed the AVRcam to respond to serial |
| bytes in the middle of tracking or dumping a frame. |
| But it wasn't really needed, and understanding the C |
| is easier :-) |
| ***********************************************************/ |
| SIGNAL(SIG_UART_RECV) |
| { |
| unsigned char tmpHead; |
| /* read the data byte, put it in the serial queue, and |
| post the event */ |
| |
| UIMgr_rxFifo[UIMgr_rxFifoHead] = UDR; |
| |
| /* now move the head up */ |
| tmpHead = (UIMgr_rxFifoHead + 1) & (UI_MGR_RX_FIFO_MASK); |
| UIMgr_rxFifoHead = tmpHead; |
| |
| /* write the serial received event to the event fifo */ |
| Exec_eventFifo[Exec_eventFifoHead] = EV_SERIAL_DATA_RECEIVED; |
| |
| /* now move the head up */ |
| tmpHead = (Exec_eventFifoHead + 1) & (EXEC_EVENT_FIFO_MASK); |
| Exec_eventFifoHead = tmpHead; |
| } |
| |