Lets write application which:
- checks out bbmagic_lib library compatibility using bbm_bt_lib_version() function
- turns on BBMagic Bluetooth communication using bbm_bt_open(..) function
- receives data from BBMagic module using bbm_bt_read(..) function
- displays information from BBMagic FLOOD module on the screen
- ends when ‘ctrl+c’ is pressed and closes BBMagic Bluetooth communication using bbm_bt_close() function
Application files
- bbmagic_lib_1.2.a – it is library for receiving data from BBMagic devices through Bluetooth Low Energy radio link. It’s for Raspberry Pi zero W and Raspberry Pi 3 which have Bluetooth LE chipset onboard.
- bbmagic_lib.h – it is bbmagic_lib header file containing definitions and constants
- libbluetooth.a – it is library from libbluetooth-dev Debian package that contains development files for using the BlueZ Linux Bluetooth library.
- bbmagic_flood_sketch.c – it is our main application ‘C’ file
- Makefile – it contains compilation instructions for make program
Project preparation
Make new directory for our project on your Raspberry Pi: mkdir bbmagic_flood_sketch
and go to it:cd bbmagic_flood_sketch
Open your favorite file editor and if you have not one try nano – its simple and intuitive:nano bbmagic_flood_sketch.c
Writing app for BBMagic FLOOD
1. Include header files required and put main function#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include "bbmagic_lib.h"
int main(void)
{
2. Variables declarationsunsigned char bbm_buf[BBLIB_FRAME_SIZE] ;
int i, data_length ;
float vcc_f ;
- bbm_buf – buffer for BBMagic FLOOD sensor data. Its size ‘BBLIB_FRAME_SIZE’ is defined in ‘bbmagic_lib.h’ file
- vcc_f – contains BBMagic FLOOD power supply voltage
- i, data_length – needs for … you will see below
3. Checking out bbmagic_lib library compatibility
If this is 0x0102 version its ok – our app can play with it.
i = bbm_bt_lib_version() ;
printf("bbm_lib_version: %0.4X - ",i) ;
if(i == 0x0102) printf("ok\n") ;
else
{
printf("nok - stop\n\n") ;
exit(1) ;
}
4. Turn on BBMagic Bluetooth communication
i = bbm_bt_open(17) ;
if(i) exit(2) ;
bbm_bt_open(..) function gets pin number with LED connected. It indicates BBMagic Bluetooth transfer. Pin number should be in range from 1 to 27. If out of this range BBMagic Bluetooth transmission indication is off.
You can connect LED in two different ways:
do
{
data_length = bbm_bt_read(bbm_buf) ;
if(data_length > 0)
{
If data arrives it is in ‘bbm_buf’ buffer.
- data_length > 0 : received ‘data_length’ bytes of data from BBMagic sensor
- data_length == 0 : there is no data received
- data_length == -1 : user break by ‘ctrl+c’
- data_length == -10 : BBMagic data authentication error
All possible returned values are defined in ‘bbmagic_lib.h’ file.
6. Is received data from BBMagic FLOOD?
switch(bbm_buf[BBMAGIC_DEVICE_TYPE])
{
case BBMAGIC_M_FLOOD :
Constants ‘BBMAGIC_DEVICE_TYPE’ and ‘BBMAGIC_M_FLOOD’ are defined in ‘bbmagic_lib.h’ file.
7. Calculating and displaying basic information from BBMagic FLOOD sensor
- Display module name:
printf("BBM_FLOOD_") ; - And then six bytes of module Bluetooth address
for(i=0; i<BBM_BT_ADDR_SIZE; i++)
printf("%0.2X", bbm_buf[BBMAGIC_DEVICE_ADDR_5 + i]) ; - Calculate and display BBMagic FLOOD power supply voltage
vcc_f = bbm_buf[BBM_FLOOD_V_SUP] ; vcc_f/=BBMAGIC_VCC_DIVIDER ;
printf(" | %0.2fV", vcc_f) ;
- Show device working time from power up (in seconds)
i =bbm_buf[BBM_FLOOD_WORKTIME_3] ; i<<=8 ;
i |=bbm_buf[BBM_FLOOD_WORKTIME_2] ; i<<=8 ;
i |=bbm_buf[BBM_FLOOD_WORKTIME_1] ; i<<=8 ;
i |=bbm_buf[BBM_FLOOD_WORKTIME_0] ;
printf(" | %4d",i) ;
- Display radio signal strength
printf(" | %ddBm | ", (signed char)bbm_buf[BBMAGIC_DEVICE_RSSI]) ;
8. Check out flood alert
If the alert flag is active we display ‘FLOOD ALERT !!’ otherwise ‘NO FLOOD :-)’
if(bbm_buf[BBM_FLOOD_ALERT_FLAGS] & BBM_FLOOD_ALERT_MASK) printf(" FLOOD ALERT !!") ;
else printf(" NO FLOOD :-)") ;
break ;
‘BBM_FLOOD_ALERT_FLAG’ and ‘BBM_FLOOD_ALERT_MASK’ constants are defined in ‘bbmagic_lib.h’ file of course.
9. Close ‘switch’ statement
If there is received data from other BBMagic sensor lets show its address and type.
default:
printf("BBM_UNKNOWN_") ;
for(i=0; i<BBM_BT_ADDR_SIZE; i++)
{
printf("%0.2X", bbm_buf[BBMAGIC_DEVICE_ADDR_5 + i]) ;
}
printf(" BBM_TYPE=%0.2X", bbm_buf[BBMAGIC_DEVICE_TYPE]) ;
break ;
} ;
10. Close ‘if(data_length > 0)’ statement
printf("\n") ;
}
11. Close ‘do{‘ statement
Wait 100 microseconds and do receive loop again untill ‘ctrl+c’ is pressed (bbm_bt_read(..) function returns -1).
usleep(100) ;
}while(data_length != -1) ;
12. Close BBMagic Bluetooth communication
If ‘ctrl+c’ pressed the program ends.
bbm_bt_close() ;
exit(0) ;
}
And done. Great job !!
