Adding MS/TP demo for ATmega168. Not finished yet.

2007-08-15 00:12:19 +00:00
parent 53bc0932ad
commit 1b364d6df1
9 changed files with 531 additions and 0 deletions
@@ -0,0 +1,160 @@
+/**************************************************************************
+*
+* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*
+*********************************************************************/
+
+/* The module handles sending data out the RS-485 port */
+/* and handles receiving data from the RS-485 port. */
+/* Customize this file for your specific hardware */
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "mstp.h"
+
+/* This file has been customized for use with ATMEGA168 */
+#include "hardware.h"
+
+/* baud rate */
+static uint32_t RS485_Baud = 38400;
+
+/****************************************************************************
+* DESCRIPTION: Initializes the RS485 hardware and variables, and starts in
+*              receive mode.
+* RETURN:      none
+* ALGORITHM:   none
+* NOTES:       none
+*****************************************************************************/
+void RS485_Initialize(void)
+{
+    /* enable Transmit and Receive */
+    UCSR0B = _BV(TXEN0) | _BV(RXEN0); 
+
+    /* Set frame format: 8data, 2stop bit */
+    UCSR0C = _BV(USBS0) | _BV(UCSZ00);
+
+    return;
+}
+
+void RS485_Cleanup(void)
+{
+
+}
+
+/****************************************************************************
+* DESCRIPTION: Returns the baud rate that we are currently running at
+* RETURN:      none
+* ALGORITHM:   none
+* NOTES:       none
+*****************************************************************************/
+uint32_t RS485_Get_Baud_Rate(void)
+{
+    return RS485_Baud;
+}
+
+/****************************************************************************
+* DESCRIPTION: Sets the baud rate for the chip USART
+* RETURN:      none
+* ALGORITHM:   none
+* NOTES:       none
+*****************************************************************************/
+bool RS485_Set_Baud_Rate(uint32_t baud)
+{
+    bool valid = true;
+
+    switch (baud) {
+        case 9600:
+        case 19200:
+        case 38400:
+        case 57600:
+        case 76800:
+        case 115200:
+            RS485_Baud = baud;
+            /* 2x speed mode */
+            BIT_SET(UCSR0A,U2X0);
+            /* configure baud rate */
+            UBRR0 = (FREQ_CPU / (8UL * RS485_Baud)) - 1;
+            /* FIXME: store the baud rate */
+            break;
+        default:
+            valid = false;
+            break;
+    }
+
+    return valid;
+}
+
+/* Transmits a Frame on the wire */
+void RS485_Send_Frame(
+    volatile struct mstp_port_struct_t *mstp_port, /* port specific data */
+    uint8_t * buffer,  /* frame to send (up to 501 bytes of data) */
+    uint16_t nbytes)   /* number of bytes of data (up to 501) */
+{
+    uint8_t turnaround_time;
+
+    /* delay after reception - per MS/TP spec */
+    if (mstp_port) {
+        /* wait about 40 bit times since reception */
+        turnaround_time = (40UL*1000UL)/RS485_Baud;
+        if (!turnaround_time) {
+            turnaround_time = 1;
+        }
+        while (mstp_port->SilenceTimer < turnaround_time) {
+            /* do nothing - wait for timer to increment */
+        };
+    }
+    while (nbytes) {
+        while (!BIT_CHECK(UCSR0A,UDRE0)) {
+            /* do nothing - wait until Tx buffer is empty */
+        }
+        UDR0 = *buffer;
+        buffer++;
+        nbytes--;
+        /* per MSTP spec */
+        if (mstp_port) {
+            mstp_port->SilenceTimer = 0;
+        }
+    }
+    while (!BIT_CHECK(UCSR0A,UDRE0)) {
+        /* do nothing - wait until Tx buffer is empty */
+    }
+
+    return;
+}
+
+/* called by timer, interrupt(?) or other thread */
+void RS485_Check_UART_Data(struct mstp_port_struct_t *mstp_port)
+{
+    if (mstp_port->ReceiveError == true) {
+        /* wait for state machine to clear this */
+    }
+    /* wait for state machine to read from the DataRegister */
+    else if (mstp_port->DataAvailable == false) {
+        /* check for data */
+        if (!BIT_CHECK(UCSR0A,RXC0)) {
+            mstp_port->DataRegister = UDR0;
+            mstp_port->DataAvailable = true;
+        }
+    }
+}