--- /dev/null
+/*-------------------------------------------------------------------------
+ ser_ir.c - source file for serial routines
+
+ Written By - Josef Wolf <jw@raven.inka.de> (1999)
+
+ Revisions:
+ 1.0 Bela Torok <bela.torok.kssg.ch> Jul. 2000
+ RTS / CTS protocol added
+
+ 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, 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+ In other words, you are welcome to use, share and improve this program.
+ You are forbidden to forbid anyone else to use, share and improve
+ what you give them. Help stamp out software-hoarding!
+
+-------------------------------------------------------------------------*/
+
+/* This file implements a serial interrupt handler and its supporting
+* routines. Compared with the existing serial.c and _ser.c it has
+* following advantages:
+* - You can specify arbitrary buffer sizes (umm, up to 255 bytes),
+* so it can run on devices with _little_ memory like at89cx051.
+* - It won't overwrite characters which already are stored in the
+* receive-/transmit-buffer.
+* - It checks receiver first to minimize probability for overruns
+* in the serial receiver.
+*/
+
+/* BUG: those definitions (and the #include) should be set dynamically
+* (while linking or at runtime) to make this file a _real_ library.
+*/
+
+/* RTS/CTS protocol howto:
+
+
+ Shematic of cable for RTS/CTS protocol (B. Torok - Jun. 2000)
+
+<- DB9 female connector -><- RS232 driver/receiver -><- 8051 system ->
+ connect to PC e.g. MAX232
+
+ RS232 TTL
+ level level
+
+ DCD DTR
+ Pin1---Pin4
+ Transmitters/Receivers
+ RXD
+ Pin2-----------------------------<<<-------------------TXD
+
+ TXD
+ Pin3----------------------------->>>-------------------RXD
+
+ GND
+ Pin5---------------------------------------------------GND
+
+ DSR CTS
+ Pin6---Pin8----------------------<<<-------------------CTS (see #define CTS)
+
+ RTS
+ Pin7----------------------------->>>-------------------RTS (see #define RTS)
+*/
+
+
+#include <8051.h>
+#include "ser_ir.h"
+
+#define TXBUFLEN 3
+#define RXBUFLEN 18 // The minimum rx buffer size for safe communications
+ // is 17. (The UART in the PC has a 16-byte FIFO.)
+// TXBUFLEN & RXBUFLEN can be highher if rxbuf[] and txbuf[] is in xdata, max size is limited to 256!
+
+#define THRESHOLD 16
+#define ENABLE 0
+#define DISABLE 1
+
+#define CTS P3_6 // CTS & RTS can be assigned to any free pins
+#define RTS P3_7
+
+static unsigned char rxbuf[RXBUFLEN], txbuf[TXBUFLEN];
+static unsigned char rxcnt, txcnt, rxpos, txpos;
+static unsigned char busy;
+
+void ser_init()
+{
+ ES = 0;
+ rxcnt = txcnt = rxpos = txpos = 0; // init buffers
+ busy = 0;
+ SCON = 0x50; // mode 1 - 8-bit UART
+ PCON |= 0x80; // SMOD = 1;
+ TMOD &= 0x0f; // use timer 1
+ TMOD |= 0x20;
+// TL1 = TH1 = 256 - 104; // 600bps with 12 MHz crystal
+// TL1 = TH1 = 256 - 52; // 1200bps with 12 MHz crystal
+// TL1 = TH1 = 256 - 26; // 2400bps with 12 MHz crystal
+ TL1 = TH1 = 256 - 13; // 4800bps with 12 MHz crystal
+
+ TR1 = 1; // Enable timer 1
+ ES = 1;
+
+ CTS = ENABLE;
+}
+
+void ser_handler(void) interrupt 4
+{
+ if (RI) {
+ RI = 0;
+ /* don't overwrite chars already in buffer */
+ if(rxcnt < RXBUFLEN) rxbuf [(rxpos + rxcnt++) % RXBUFLEN] = SBUF;
+ if(rxcnt >= (RXBUFLEN - THRESHOLD)) CTS = DISABLE;
+ }
+
+ if (TI) {
+ TI = 0;
+ if (busy = txcnt) { /* Assignment, _not_ comparison! */
+ txcnt--;
+ SBUF = txbuf[txpos++];
+ if(txpos >= TXBUFLEN) txpos = 0;
+ }
+ }
+}
+
+void ser_putc(unsigned char c)
+{
+ while(txcnt >= TXBUFLEN); // wait for room in buffer
+
+ while(RTS == DISABLE);
+
+ ES = 0;
+ if (busy) {
+ txbuf[(txpos + txcnt++) % TXBUFLEN] = c;
+ } else {
+ SBUF = c;
+ busy = 1;
+ }
+ ES = 1;
+}
+
+unsigned char ser_getc(void)
+{
+ unsigned char c;
+
+ while (!rxcnt) { // wait for a character
+ CTS = ENABLE;
+ }
+
+ ES = 0;
+ rxcnt--;
+ c = rxbuf[rxpos++];
+ if (rxpos >= RXBUFLEN) rxpos = 0;
+ ES = 1;
+ return (c);
+}
+
+#pragma SAVE
+#pragma NOINDUCTION
+void ser_puts(unsigned char *s)
+{
+ unsigned char c;
+ while (c= *s++) {
+ if (c == LF) ser_putc(CR);
+ ser_putc (c);
+ }
+}
+#pragma RESTORE
+
+void ser_gets(unsigned char *s, unsigned char len)
+{
+ unsigned char pos, c;
+
+ pos = 0;
+ while (pos <= len) {
+ c = ser_getc();
+ if (c == CR) continue; // discard CR's
+ s[pos++] = c;
+ if (c == LF) break; // NL terminates
+ }
+ s[pos] = '\0'; // terminate string
+}
+
+unsigned char ser_can_xmt(void)
+{
+ return TXBUFLEN - txcnt;
+}
+
+unsigned char ser_can_rcv(void)
+{
+ return rxcnt;
+}
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projects / fw / sdcc / blobdiff