Timer based UART for sending and receiving bytes on the FX2

examples/download.sh

@@ -0,0 +1,15 @@
+#!/bin/bash -e
+
+DEVS=$(lsusb|grep -E '(2a19|16c0|04b4|1d50|fb9a|1443)' |sed 's/:.*//;s/Bus //;s/Device //;s/ /\//')
+
+if [ -z "$1" ]; then
+    echo "$0: usage: $0 <file>"
+    exit 1;
+fi
+
+for dev in $DEVS;do
+    echo "Downloading $1 to $dev"
+    /sbin/fxload -D /dev/bus/usb/$dev -t fx2lp -I $1
+done
+
+exit 0

examples/uart_timer/Makefile

@@ -0,0 +1,8 @@
+FX2LIBDIR=../..
+BASENAME = uart_timer
+SOURCES=uart_timer.c
+DSCR_AREA=
+INT2JT=
+include $(FX2LIBDIR)/lib/fx2.mk
+fx2_download:
+	../download.sh build/$(BASENAME).ihx

examples/uart_timer/uart_timer.c

@@ -0,0 +1,61 @@
+/**
+ * Copyright (C) 2009 Ubixum, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ **/
+#include <fx2regs.h>
+#include <stdio.h>
+#include <fx2ints.h>
+#include <uart/api.h>
+#include <uart/timer_uart.h>
+#include <fx2macros.h>
+
+//Used for setting the baud rate.
+//Currently unimplemented
+enum uart_baud baud;
+//Extern declaration. 
+extern void process_isr();
+void main(void)
+{
+    baud = BAUD_9600;
+    uartX_init(baud);
+    printf("Hello");
+    while (TRUE)
+   {
+      uart_rx_service();
+      uart_tx_service();
+
+   }
+}
+
+void putchar(char c)
+{
+    uartX_tx(c);
+}
+
+
+/**
+ * \brief This function is actually an ISR
+ * It is called periodically to check if data is ready to be transmitted
+ * The receive logic looks at the rx pin, sampling it continously. The moment
+ * a start bit is detected, it begins shifting the data in
+ * and finally sets a flag stating the receive is complete. This flag is reset
+ * in the uart_rx_service. This helps achieve non blocking behaviour.
+ **/
+void timer1_isr ()
+__interrupt TF1_ISR
+{
+ process_isr();
+}

include/uart/api.h

@@ -0,0 +1,79 @@
+/** \file include/uart/api.h
+ * This file is for defining a common API for accessing UARTs.
+ **/
+
+#ifndef UART_API_H
+#define UART_API_H
+
+#include "fx2types.h"
+#include "stdarg.h"
+
+/**
+ * enum Standard available baud rates
+ *
+**/
+enum uart_baud { BAUD_2400, BAUD_4800, BAUD_9600, BAUD_19200, BAUD_38400, BAUD_57600, BAUD_115200, BAUD_ANY, BAUD_FASTEST };
+
+/**
+ * \brief initalizes UART.
+ * Returns 0 if initialization is successful.
+ * \param rate See uartX_set_baud()
+ **/
+BOOL uartX_init(enum uart_baud rate, ...);
+
+/**
+ * \brief Sets the UART baud rate to one of the allowed parameters.
+ *   Possible Baud rates:
+ *    \li 2400
+ *    \li 4800
+ *    \li 9600
+ *    \li 19200
+ *    \li 28800
+ *    \li 38400
+ *    \li 57600
+ *    \li 115200
+ * Returns 0 if successful. 
+**/
+BOOL uartX_set_baud(enum uart_baud rate);
+
+/**
+ * \brief Returns the baud rate currently being used.
+**/
+enum uart_baud uartX_get_baud();
+
+/**
+ * \brief transmits data through UART 
+ * \param c The character to be sent out
+**/
+
+void uartX_tx(char c);
+
+/**
+ * \brief Returns if the transmit is blocking or not
+ * TRUE - Blocking
+ * FALSE -Non Blocking
+**/
+
+BOOL uartX_tx_willblock();
+
+/**
+ * \brief receives data through UART.
+ * Returns one byte at a time from the queue
+ *
+**/
+char uartX_rx();
+
+/**
+ * \brief Returns if the receive is blocking or not
+ * 0 - Non Blocking
+ * 1 - Blocking
+**/
+BOOL uartX_check_rx_blocking();
+
+/**
+ * \brief Returns count number of bytes present in the buffer
+ *
+**/
+BYTE uartX_check_receive_buffer();
+
+#endif

include/uart/timer_uart.h

@@ -0,0 +1,43 @@
+#ifndef TIMER_UART_H
+#define TIMER_UART_H
+#include "fx2regs.h"
+#include "fx2types.h"
+
+/**
+ * Enum for controlling transmitter state
+ * Only 2 states in the enum, it is either
+ * in IDLE or BUSY
+**/
+enum uart_tx_state{IDLE, BUSY};
+
+/**
+ * Enum for controlling receiver state
+ * Only 4 states in the enum
+ * 0x00 - IDLE
+ * 0x01 - Data Reception complete
+ * 0x02 - Start bit detect
+ * 0x03 - Data currently being read
+**/
+enum uart_rx_state{IDLE_RX,DATA_COMPLETE,START_DETECT,BUSY_RX};
+
+void timer_init();
+void softuart_init( void );
+void uart_tx_service();
+void uart_rx_service();
+void QueueInitTX(void);
+__bit QueuePutTX(unsigned char data);
+__bit QueueGetTX(unsigned char  *old);
+__bit QueueCheckTX();
+void QueueInitRX(void);
+__bit QueuePutRX(unsigned char data);
+__bit QueueGetRX(unsigned char * old);
+__bit QueueCheckRX();
+void process_isr();
+extern unsigned char volatile tx_buffer;
+extern unsigned char volatile rx_buffer;
+extern unsigned char volatile tx_count;
+extern unsigned char volatile rx_count;
+extern unsigned char volatile tx_bits_sent;
+extern unsigned char volatile rx_bits_rcvd;
+extern unsigned char volatile rx_busy;
+#endif

lib/Makefile

@@ -15,7 +15,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
 AS8051?=sdas8051
-SOURCES = serial.c i2c.c delay.c setupdat.c gpif.c eputils.c $(wildcard interrupts/*.c)
+SOURCES = serial.c i2c.c delay.c setupdat.c gpif.c eputils.c $(wildcard interrupts/*.c) $(wildcard uart/*.c)
 FX2_OBJS = $(patsubst %.c,%.rel, $(SOURCES)) usbav.rel
 INCLUDES = -I../include
 SDCC = sdcc -mmcs51 $(SDCCFLAGS)