From a50a2d888f6d2f51a8bc2ccd7c1aaf71ecbd7c5a Mon Sep 17 00:00:00 2001 From: "David A. Mellis" Date: Sat, 8 Mar 2008 21:30:00 +0000 Subject: [PATCH] Added timeout (in microseconds) parameter to pulseIn(). Defaults to 1000000 (1 second). --- hardware/cores/arduino/WProgram.h | 2 ++ hardware/cores/arduino/wiring.h | 3 ++- hardware/cores/arduino/wiring_pulse.c | 20 +++++++++++++------- todo.txt | 8 ++++++-- 4 files changed, 23 insertions(+), 10 deletions(-) diff --git a/hardware/cores/arduino/WProgram.h b/hardware/cores/arduino/WProgram.h index 206cdaca9..1fba738cf 100755 --- a/hardware/cores/arduino/WProgram.h +++ b/hardware/cores/arduino/WProgram.h @@ -10,6 +10,8 @@ #ifdef __cplusplus #include "HardwareSerial.h" +unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout = 1000000L); + // WMath prototypes long random(long); long random(long, long); diff --git a/hardware/cores/arduino/wiring.h b/hardware/cores/arduino/wiring.h index df43e6c67..26cba9ea4 100755 --- a/hardware/cores/arduino/wiring.h +++ b/hardware/cores/arduino/wiring.h @@ -87,6 +87,7 @@ extern "C"{ #define clockCyclesPerMicrosecond() ( F_CPU / 1000000L ) #define clockCyclesToMicroseconds(a) ( (a) / clockCyclesPerMicrosecond() ) +#define microsecondsToClockCycles(a) ( (a) * clockCyclesPerMicrosecond() ) typedef uint8_t boolean; typedef uint8_t byte; @@ -118,7 +119,7 @@ void printIntegerInBase(unsigned long n, unsigned long base); unsigned long millis(void); void delay(unsigned long); void delayMicroseconds(unsigned int us); -unsigned long pulseIn(uint8_t pin, uint8_t state); +unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout); void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, byte val); diff --git a/hardware/cores/arduino/wiring_pulse.c b/hardware/cores/arduino/wiring_pulse.c index 642a5a22b..01571145b 100755 --- a/hardware/cores/arduino/wiring_pulse.c +++ b/hardware/cores/arduino/wiring_pulse.c @@ -26,10 +26,10 @@ #include "pins_arduino.h" /* Measures the length (in microseconds) of a pulse on the pin; state is HIGH - * or LOW, the type of pulse to measure. Works on pulses from 10 microseconds - * to 3 minutes in length, but must be called at least N microseconds before - * the start of the pulse. */ -unsigned long pulseIn(uint8_t pin, uint8_t state) + * or LOW, the type of pulse to measure. Works on pulses from 2-3 microseconds + * to 3 minutes in length, but must be called at least a few dozen microseconds + * before the start of the pulse. */ +unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout) { // cache the port and bit of the pin in order to speed up the // pulse width measuring loop and achieve finer resolution. calling @@ -39,17 +39,23 @@ unsigned long pulseIn(uint8_t pin, uint8_t state) uint8_t stateMask = (state ? bit : 0); unsigned long width = 0; // keep initialization out of time critical area + // convert the timeout from microseconds to a number of times through + // the initial loop; it takes 16 clock cycles per iteration. + unsigned long numloops = 0; + unsigned long maxloops = microsecondsToClockCycles(timeout) / 16; + // wait for the pulse to start while ((*portInputRegister(port) & bit) != stateMask) - ; + if (numloops++ == maxloops) + return 0; // wait for the pulse to stop while ((*portInputRegister(port) & bit) == stateMask) width++; // convert the reading to microseconds. The loop has been determined - // to be 10 clock cycles long and have about 12 clocks between the edge + // to be 10 clock cycles long and have about 16 clocks between the edge // and the start of the loop. There will be some error introduced by // the interrupt handlers. - return clockCyclesToMicroseconds(width * 10 + 12); + return clockCyclesToMicroseconds(width * 10 + 16); } diff --git a/todo.txt b/todo.txt index 87d335220..0663df9a5 100644 --- a/todo.txt +++ b/todo.txt @@ -8,9 +8,9 @@ Improve preprocessing of sketches: - [done] Insert prototypes at a better spot in the code (after pre-processor directives). - [done] Don't move #include statements. - [done] Better determine which functions need prototypes -Update version of the FTDI drivers. -Incorporate ladyada's new SoftwareSerial library. +Update version of the FTDI drivers (Windows). Add timeout parameter to pulseIn(). +[done] Update version of the FTDI drivers (Mac). [done] Allow disabling of serial flushing before upload (for the Arduino BT). [done] Modify parallel port programmer burning (add -F, lower or remove delay). [done] Allow uploading using a hardware programmer. @@ -22,8 +22,11 @@ Add timeout parameter to pulseIn(). AVR +Add parameter to shiftOut() for specifying a number of bits. +Add parameter to Serial.print[ln](x, BYTE) for specifying number of bits. Add support for ATmega1280 (e.g. timers, external interrupts, multiple serial ports). Add weak attribute to signal handlers (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1203798214) +Incorporate ladyada's new SoftwareSerial library. Good way to receive multiple values / complex messages over the serial port. Floating point support in the map() function. Consider moving millis() to timer 1, and configuring it so the interrupt is generated once a millisecond. @@ -64,6 +67,7 @@ Move to ant for build process (limitations: can't build bootloader, can't build DOCUMENTATION +Get good top-down, well-lit, plain-white-background photos of the Arduino boards. Electronics reference a la Wiring. Documentation for moving from Arduino to custom PCBs. Examples should demonstrate use of functions.