Peeking at Espruino Board Timers 2, 3, 4, and 5

FreqT5A1.js Measuring Frequency Using Timer 5 and Pin A1
Uses Pin B0 as a frequency source to test.

/* 
FreqT5A1.js
Frequency measurement using
Pin A1 on Timer 5
Use Pin B0 of  Timer3 as a source of square waves to measure
Connect Pin B0 to Pin A1

zero counter,
start counter,
count for timebase ms,
stop counter,
display count as frequency in Hz as adjusted by timebase
repeat

//Now displays timers 1 thru 14
This was run on an Espruino board

To clear the timer requires the board to be powered down or the reset button

*/
/*
http://www.keil.com/dd/docs/datashts/st/­stm32f10xxx.pdf
*/
var TIM5=0x40000C00;
//Timer register offsets
var CR1=0x0;
var CR2=0x04;
var SMCR=0x08;
var DIER=0x0c;
var SR=0x10;
var EGR=0x14;
var CCMR1=0x18;
var CCMR2=0x1c;
var CCER=0x20;
var CNT=0x24;
var PSC=0x28;
var ARR=0x2c;
var CCR1=0x34;
var CCR2=0x38;
var CCR3=0x3c;
var CCR4=0x40;
var DCR=0x48;
var DMAR=0x4c;

// use B0 as a frequency source to measure
analogWrite(B0,0.5,{ freq : 1000 });

//setup pin A1 as the counter input
A1.mode('input');

//timer 5 clock
var RCCbase=0x40021000;
var APB1ENR=RCCbase+0x1c;
var APB1RST=RCCbase+0x10;
var APB2ENR=RCCbase+0x18;

//turn on timer 5 clock
 poke8(APB1ENR,(peek8(APB1ENR)&0xf7)|0x08­);

//reset timer 5
 poke8(APB1RST,(peek8(APB1RST)&0xf7)|0x08­);
 poke8(APB1RST,(peek8(APB1RST)^0x08));

//disable timer 5
  poke32(TIM5+CR1,0x80);

//setup timer 5
poke16(TIM5+CCMR1,0x0100);
poke16(TIM5+CCER,0x0000); 
poke16(TIM5+SMCR,0x0067);
poke32(TIM5+CNT,0);
//Preload timer
poke32(TIM5+EGR,1);
//Enable timer 5
//poke32(TIM5+CR1,0x81); 

var timebase=2000;
setInterval(function () {
  poke32(TIM5+CR1,0x80);
  console.log("CNT="+peek32(TIM5+CNT)*1000­/timebase +" Hz.");
  poke32(TIM5+CNT,1);
  poke32(TIM5+CR1,0x81);
}, timebase);

1 Attachment

• FreqT5A1.js