103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
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/**
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* Copyright (C) 2009 Ubixum, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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**/
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#include <fx2regs.h>
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#include <fx2macros.h>
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#include <serial.h>
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/**
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* using the comp port implies that timer 2 will be used as
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* a baud rate generator. (Don't use timer 2)
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**/
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void
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sio0_init(WORD baud_rate)
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__critical
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{ // baud_rate max should be 57600 since int=2 bytes
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WORD hl; // hl value for reload
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BYTE mult; // multiplier for clock speed
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DWORD tmp; // scratch for mult/divide
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// 0 = 12mhz, 1=24mhz, 2=48mhz
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mult = CPUFREQ == CLK_12M ? 1 : CPUFREQ == CLK_24M ? 2 : 4; // since only 3 clock speeds, fast switch instead of doing 2^clock speed pow(2,clkspd)
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// set the clock rate
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// use clock 2
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RCLK = 1;
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TCLK = 1;
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// RCAP2H:L = 0xFFFF - CLKOUT / 32 x baud_rate
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// in order to round to nearest value..
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// tmp * 2 // double
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// tmp / rate // do the divide
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// tmp + 1 // add one (which is like adding 1/2)
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// tmp / 2 // back to original rounded
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tmp = mult * 375000L * 2;
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tmp /= baud_rate;
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tmp += 1;
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tmp /= 2;
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hl = 0xFFFF - (WORD) tmp;
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RCAP2H = MSB(hl);
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// seems that the 24/48mhz calculations are always one less than suggested values
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// trm table 14-16
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RCAP2L = LSB(hl) + (mult > 0 ? 1 : 0);
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TR2 = 1; // start the timer
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// set up the serial port
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SM0 = 0;
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SM1 = 1; // serial mode 1 (asyncronous)
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SM2 = 0; // has to do with receiving
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REN = 1; // to enable receiving
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PCON |= 0x80; // SET SMOD0, baud rate doubler
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TI = 1; // we send initial byte
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}
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char
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getchar()
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{
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char c;
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while (!RI);
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c = SBUF0;
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RI = 0;
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return c;
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}
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void
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_transchar(char c)
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{
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while (!TI); // wait for TI=1
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TI = 0;
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SBUF0 = c;
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}
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void
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putchar(char c)
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{
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if (c == '\n')
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_transchar('\r'); // transmit \r\n
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_transchar(c);
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if (c == '\r')
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_transchar('\n'); // transmit \r\n
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}
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