Posted on January 19, 2015 at 06:32
I will post the matlab code also,
So on my stm code and plot why i dont see the glitch? Is it because i sample so fast before the serial ouput?
Did anyone else encounterd such issue? This setup is done in the absence of all hardware setup, its used for pid control on a quadcopter platform, so i have to wait for mottors and esc to arhive.
I just wanted to test my pid engine using a simple adc input from a potentiometer, but not seeing the pid glitch i cant form an idea about seting the relative values for the KP,KI and KD parameters.
Hello all, i am trying to do a simple pid simulation with discovery board and matlab.
However i dont think that my data is runing as it should, what i want to say is that i dont get the usualy rising spike edge from the pid. The pid calculation is done in the microcontroler, matlab only reads the two serial datas separated by @ character.int main(void){
SystemInit();
cycleCounterInit();
SysTick_Config(SystemCoreClock / 1000);
lcd_init();
init_leds();
serial_init();
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
ADC_CommonInitTypeDef ADC_CommonInitStructure;
ADC_InitTypeDef ADC_InitStructure;
/* ADC Common Init */
ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&ADC_CommonInitStructure);
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = DISABLE; // 1 Channel
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; // Conversions Triggered
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None; // Manual
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T2_TRGO;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion = 1;
ADC_Init(ADC1, &ADC_InitStructure);
/* ADC1 regular channel 11 configuration */
ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_144Cycles); // PC1
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
char adctxt[10];
char pidtxt[10];
float Kp=1;
float Ki=0;
float Kd=0;
float windupGuard=2;
float SetPoint=2.0;
float input=0;
float error=0;
float output=0;
float current_time=0;
float last_time=0;
float deltaT=0;
float integral=0;
float derivative=0;
float prevErr=0;
while(1){
loop_20hz(){ // a 20hz interrupt every 20000 us systick count
ADC_SoftwareStartConv(ADC1);
while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);
float bbb = ADC_GetConversionValue(ADC1);
bbb=bbb*5/4096;
input=bbb;
current_time = micros(); // returns curent time from systick in uS
deltaT = (current_time - last_time)/1000000.0;
error=SetPoint-input;
integral=constrain((integral+error*deltaT),0,windupGuard);
derivative = (input-prevErr)/deltaT;
output =(Kp*error)+(Ki*integral)+(Kd*derivative);
prevErr =input;
last_time = micros(); // returns curent time from systick in uS
if(output<0){ output=0; }
sprintf(txtadc,''%0.1f'',input);
sprintf(pidtxt,''%0.1f'',output);
USART_Puts(txtadc);
USART_Puts(''@''); // send to matlab curent adc value
USART_Puts(pidtxt); // sends to matlab curent pid output
USART_Puts(''\r\n''); // sends the terminator chars
}
}
}blue line - is adc read from pot ( when potentiometer is idle it measures about 2.3 volts)
red line - is the pid output
I will post the matlab code also,
clc
clear all
if ~isempty(instrfind)
fclose(instrfind);
delete(instrfind);
end
close all
clc
disp('Serial Port Closed')
clear
clc
serialPort = 'COM7'; % define COM port #
plotTitle = 'Serial Data Log'; % plot title
xLabel = 'Elapsed Time (s)'; % x-axis label
yLabel = 'Data'; % y-axis label
plotGrid = 'on'; % 'off' to turn off grid
min =0; % set y-min
max = 3; % set y-max
scrollWidth = 5; % display period in plot, plot entire data log if <= 0
delay = .01; % make sure sample faster than resolution
%Define Function Variables
time = 0;
data = 0;
count = 0;
bdata = 0;
btime = 0;
%Set up Plot
plotGraph = plot(time,data,'b');
title(plotTitle,'FontSize',25);
xlabel(xLabel,'FontSize',15);
ylabel(yLabel,'FontSize',15);
axis([0 10 min max]);
grid(plotGrid);
%Open Serial COM Port
s = serial(serialPort)
set(s,'DataBits',8);
set(s,'StopBits',1);
set(s,'BaudRate',9600 );
set(s,'Parity','none');
disp('Close Plot to End Session');
fopen(s);
tic
while ishandle(plotGraph) %Loop when Plot is Active
zz=fscanf(s); % - HERE SCANS THE SERIAL INPUT FROM STM
uu=regexp(zz,'@', 'split');
dat =sscanf(uu{1},'%f');
bdat =sscanf(uu{2},'%f');
if(~isempty(dat) && isfloat(dat)&& isfloat(bdat)) %Make sure Data Type is Correct
count = count + 1;
time(count) = toc; %Extract Elapsed Time
data(count) = dat(1); %Extract 1st Data Element
bdata(count) = bdat(1);
set(plotGraph,'XData',time(time > time(count)-scrollWidth),'YData',data(time > time(count)-scrollWidth));hold on
btime=time;
plot(btime,bdata,'r');hold off
axis([time(count)-scrollWidth time(count) min max]);
else
set(bplotGraph,'XData',time,'YData',bdata);
axis([0 time(count) min max]);
end
drawnow;
end
%Close Serial COM Port and Delete useless Variables
fclose(s);
clear count dat delay max min plotGraph plotGrid plotTitle s ...
scrollWidth serialPort xLabel yLabel;
disp('Session Terminated...');