Raspberry Pi using Scratch as HMI, involving wiringPi and Qt for programming and open source hardware boards from electronics.cat.
Boards used in the video :
Raspberry Pi : Raspberry Pi
set05_08 : 3Bpi - Level translator board for Raspberry Pi
set05_04 : Input Board
set05_02 : Relays Board
set01_04 : Inputs and Outputs (microswitch + LEDs)
Requirements :
- Qt4 tool chain installed on Raspberry Pi
- wiringPi installed on Raspberry Pi
- Connect reliable hardware to GPIO (be aware Raspberry Pi use 3.3V internally)
To compile Qt code using wiringPi on Raspberry Pi :
- Uncompress Qt code using wiringPi
- On the qtPi04 directory, type on the terminal :
qmake
make
To run this sample :
- Run Scratch and open Scratch’s code
- Type on terminal :
sudo ./qtPi04
pi@raspberrypi ~/code/wiringPi/qtPi04 $ sudo ./qtPi04
3Bpi + Raspberry Pi + Qt + wiringPi test program
TCP disconnected
Scratch cannot be connected through TCP <= If Scratch is not running
“xxxx1111″
pi@raspberrypi ~/code/wiringPi/qtPi04 $ sudo ./qtPi04
3Bpi + Raspberry Pi + Qt + wiringPi test program
TCP connected
Scratch connected through TCP <= If Scratch is running with Scratch’s code opened
“xxxx1111″
“xxxx1101″ <= When a switch is pressed
“sensor-update note 60 beats 0.4″
“broadcast “0×3E_SW1_pressed”"
“xxxx1111″
“sensor-update note 62 beats 0.4″
“broadcast “0×3E_SW1_unpressed”"
As a tip to understand how it is programmed this is a C code using wiringPi and this is its translation to C++ using Qt and wiringPi.
This post is a proof of concept using Raspberry Pi, wiringPi, 3Bpi and other OSHW boards.
wiringPi is a GPIO Interface library for the Raspberry Pi written by Gordon Hederson ( projects.drogon.net). It is designed to be familiar to people who have used the Arduino “wiring” system. And it is very friendly and convenient to use interfacing external boards to GPIO’s Raspberry Pi.
Video :
To compile the code having installed wiringPi on Raspberry Pi :
gcc wPi00.c -o wPi00 -lwiringPi
Boards used in the video :
Raspberry Pi : Raspberry Pi
set05_08 : 3Bpi - Level translator board for Raspberry Pi
set05_02 : Relays Board
set01_04 : Inputs and Outputs (microswitch + LEDs)
In this specific sample, 3Bpi is used as a connector translator among boards. Translation between 3.3V and 5V is not required to drive outputs .
wiringPi can use different pin numbering. To translate by default pin numbering to 3Bpi ports I have used this global variables :
uint8_t byP2wPiMaster[] = {19,20,15,16}, byP2wPiSlave[] = {20,19,16,15};
uint8_t byP3wPi[] = {18,17,1,11,10,12,13,14}; /* [0]:LSB, [7]:MSB*/
uint8_t byP4wPi[] = {9,8,5,6,4,2,3,7}; /* [0]:LSB, [7]:MSB*/
And to define which pins are output or input I have used this notation (In this sample all the pins modes are outputs) :
#define P3_SETUP 0×00 /* 0 : Output, 1 : Input*/
#define P4_SETUP 0×00 /* 0 : Output, 1 : Input*/
Using these constants to call pinMode() :
v3BpiP3pinMode(P3_SETUP);
v3BpiP4pinMode(P4_SETUP);
Some electronics.cat’s boards are using nibbles to read inputs and to write outputs (for instance set05_02 Relays Board or set05_04 Input Board). For this reason these functions have been created :
void v3BpiP3digitalWrite(uint8_t by){
v3BpiHighNibbleP3digitalWrite(by);
v3BpiLowNibbleP3digitalWrite(by);
}
void v3BpiP4digitalWrite(uint8_t by){
v3BpiHighNibbleP4digitalWrite(by);
v3BpiLowNibbleP4digitalWrite(by);
}
These functions call to digitalWrite().
Code of this proof of concept can be downloaded clicking on this link.