Create xBee_driver low-level library

code/ViveBeacons/ViveBeacons.cydsn/ViveBeacons.cyprj

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code/ViveBeacons/ViveBeacons.cydsn/XBee_driver.c

@@ -0,0 +1,234 @@
+/* ============================================================================
+ *
+ *  Copyright (C) 2019 - Evan Roué
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  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 Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * ============================================================================
+*/
+
+#include <stdlib.h>
+#include "XBee_driver.h"
+
+/*
+    ---------------------------------------------------------------------------
+    A PSoC Library to communicate with xBee S1
+
+    Link to the documentation :
+    https://www.digi.com/resources/documentation/digidocs/pdfs/90000982.pdf
+
+    NOTE : This library can be used with xBee S3, as it supports IEEE 802.15.4
+    ---------------------------------------------------------------------------
+*/
+
+/*
+    --------------
+    Public methods
+    --------------
+*/
+
+XBee_driver* XBee_driver_create() {
+    XBee_driver* xBee_driver = (XBee_driver*) malloc(1*sizeof(XBee_driver));
+
+    xBee_driver->callbacks = NULL;
+    xBee_driver->callbacks_count = 0;
+
+    return xBee_driver;
+}
+
+void XBee_driver_init(XBee_driver *xBee_driver) {
+    (void)xBee_driver; // suppress "unused" warning
+    UART_XBEE_Start();
+}
+
+/*
+    ---------------------------------------------------------------------------
+    Name : Register callback
+    Description : Associate a callback with a specific xBee API frame type.
+    ---------------------------------------------------------------------------
+*/
+
+void XBee_driver_register_callback(XBee_driver *xBee_driver, uint8_t frame_type, void (*callback_function)(uint8_t *frame_buffer)) {
+    xBee_driver->callbacks = (xBee_driver_callback *) realloc(xBee_driver->callbacks, (xBee_driver->callbacks_count + 1)*sizeof(xBee_driver_callback));
+
+    (xBee_driver->callbacks[xBee_driver->callbacks_count]).frame_type = frame_type;
+    (xBee_driver->callbacks[xBee_driver->callbacks_count]).callback_function = callback_function;
+    xBee_driver->callbacks_count++;
+}
+
+void XBee_driver_create_TX_request(XBee_driver *xBee_driver, XBee_TX_frame *xBee_TX_frame, uint16_t *xBee_TX_frame_length, const uint16_t dest_address, const uint8_t payload[], const uint8_t payload_length) {
+    (void) xBee_driver; // suppress warning
+
+    *xBee_TX_frame_length = 1 + 1 + 2 + 1 + payload_length;
+    uint8_t frame_id = 0x01; // for future use
+    uint8_t frame_options = 0x0; // for future use
+
+    // Forge the frame
+    xBee_TX_frame->type = TX_16_REQUEST;
+    xBee_TX_frame->id = frame_id;
+    xBee_TX_frame->dest_addr = SWAP_ENDIAN_16(dest_address);
+    xBee_TX_frame->options = frame_options;
+    memcpy(xBee_TX_frame->data, payload, payload_length);
+}
+
+/*
+    ---------------------------------------------------------------------------
+    Name : Send
+    Description : Send any frame to the local xBee.
+
+    WARNING : This is a blocking function.
+    ---------------------------------------------------------------------------
+*/
+
+void XBee_driver_send(XBee_driver *xBee_driver, const void *xBee_frame, const uint16_t frame_length) {
+    (void) xBee_driver; // suppress warning
+
+    uint16_t length = 2 + frame_length + 1; // length without 0x7E (start byte)
+    const uint8_t *frame = (const uint8_t *) xBee_frame;
+
+    // Create buffer
+    uint8_t *buffer = (uint8_t *) malloc(length*sizeof(uint8_t));
+
+    // Fill in the buffer
+    buffer[0] = (frame_length >> 8);
+    buffer[1] = (frame_length & 0xFF);
+
+    memcpy(buffer + 2, frame, frame_length);
+
+    // Checkum forever !
+    buffer[length - 1] = XBee_driver_compute_checksum(frame, frame_length);
+
+    // Send to xBee and escaping bytes if needed
+    UART_XBEE_PutChar(0x7E);
+    for(int i = 0; i < length; i++)
+        XBee_driver_send_byte(xBee_driver, buffer[i]);
+
+    free(buffer);
+}
+
+/*
+    ---------------------------------------------------------------------------
+    Name : Check commands
+    Description : Process the reception of xBee API frame and call the
+    registered callback associated to the frame type received.
+
+    WARNING : This is a blocking function.
+    ---------------------------------------------------------------------------
+*/
+
+// TODO : Convert to non-blocking, using state machine method ?
+void XBee_driver_check_commands(XBee_driver *xBee_driver) {
+    uint16_t character = (uint8_t) UART_XBEE_GetByte();
+
+    if(character == 0x7E) { // Start of frame
+        // Get length
+        uint8_t length_buffer[2];
+        length_buffer[0] = XBee_driver_get_byte(xBee_driver);
+        length_buffer[1] = XBee_driver_get_byte(xBee_driver);
+        uint16 frame_length = (length_buffer[0] << 8) | length_buffer[1];
+
+        // Get API frame itself
+        uint8_t *frame_buffer = (uint8_t *) malloc(frame_length*sizeof(uint8_t));
+        for(int i = 0; i < frame_length; i++)
+            frame_buffer[i] = XBee_driver_get_byte(xBee_driver);
+
+        // Get checksum and do the check
+        uint8_t checksum = XBee_driver_get_byte(xBee_driver);
+
+        if(XBee_driver_compute_checksum(frame_buffer, frame_length) == checksum) {
+            uint8_t frame_type = frame_buffer[0];
+
+            // Call the correct callback
+            for(int i = 0; i < xBee_driver->callbacks_count; i++) {
+                if((xBee_driver->callbacks[i]).frame_type == frame_type) {
+                    (*((xBee_driver->callbacks[i]).callback_function))(frame_buffer);
+                    break;
+                }
+            }
+        }
+
+        free(frame_buffer);
+    }
+}
+
+/*
+    ---------------------------------------------------------------------------
+    Name : Compute checksum
+    Description : Compute the checksum for API frames, as indicated in the xBee
+    documentation.
+    ---------------------------------------------------------------------------
+*/
+
+uint8_t XBee_driver_compute_checksum(const uint8_t *frame, const uint16_t frame_length) {
+    uint8_t acc = 0x0;
+
+    for(int i = 0; i < frame_length; i++) {
+        acc = (uint8_t) (acc + frame[i]);
+    }
+
+    return 0xFF - acc;
+}
+
+/*
+    --------------
+    Private methods
+    --------------
+*/
+
+/*
+    ---------------------------------------------------------------------------
+    Name : Get byte
+    Description : Get a byte of raw data from the UART link. This function
+    takes care of escaped characters in xBee API Mode 2.
+
+    WARNING : This is a blocking function.
+    ---------------------------------------------------------------------------
+*/
+
+uint8_t XBee_driver_get_byte(XBee_driver *xBee_driver) {
+    (void) xBee_driver; // suppress warning
+
+    while(UART_XBEE_GetRxBufferSize() < 1);
+    uint8_t received_byte = (uint8_t) UART_XBEE_GetByte();
+
+    if(received_byte == 0x7D) { // Escaping character
+        while(UART_XBEE_GetRxBufferSize() < 1);
+        received_byte = (uint8_t) UART_XBEE_GetByte();
+        return received_byte ^ 0x20; 
+    } else
+        return received_byte; 
+}
+
+/*
+    ---------------------------------------------------------------------------
+    Name : Send byte
+    Description : Send a byte of raw data to the UART link. This function takes
+    care of escaped characters in xBee API Mode 2.
+
+    WARNING : This is a blocking function.
+    ---------------------------------------------------------------------------
+*/
+
+void XBee_driver_send_byte(XBee_driver *xBee_driver, uint8_t byte) {
+    (void) xBee_driver; // suppress warning
+
+    if(byte == 0x7E || byte == 0x7D || byte == 0x11 || byte == 0x13) {
+        // Escape the byte
+        UART_XBEE_PutChar(0x7D);
+        UART_XBEE_PutChar(byte ^ 0x20);
+    } else
+        UART_XBEE_PutChar(byte);
+}
+
+/* [] END OF FILE */