cache lastValue (#6)

- change behaviour
  - cache lastValue as calculated by **ready()**
- change **uint16_t value()** signature
- update examples
- update GitHub actions
- minor edits

Author: RobTillaart

.github/FUNDING.yml

@@ -1,4 +1,5 @@
 # These are supported funding model platforms
 
-github: RobTillaart
+github: RobTillaart  
+custom: "https://www.paypal.me/robtillaart"
 

.github/workflows/arduino-lint.yml

@@ -1,12 +1,12 @@
-
 name: Arduino-lint
 
 on: [push, pull_request]
 jobs:
   lint:
     runs-on: ubuntu-latest
+    timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: arduino/arduino-lint-action@v1
         with:
           library-manager: update

.github/workflows/arduino_test_runner.yml

@@ -1,14 +1,14 @@
----
 name: Arduino CI
 
 on: [push, pull_request]
 
 jobs:
   runTest:
     runs-on: ubuntu-latest
+    timeout-minutes: 20
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 2.6

.github/workflows/jsoncheck.yml

@@ -9,10 +9,11 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
+    timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: json-syntax-check
-        uses: limitusus/json-syntax-check@v1
+        uses: limitusus/json-syntax-check@v2
         with:
           pattern: "\\.json$"
 

AsyncAnalog.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: AsyncAnalog.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.6
+// VERSION: 0.2.0
 //    DATE: 2018-09-05
 // PURPOSE: Async version of analogRead, prevent blocking wait
 //     URL: https://github.com/RobTillaart/AsyncAnalog
@@ -26,15 +26,15 @@ AsyncAnalog::AsyncAnalog(const uint8_t pin)
 void AsyncAnalog::start()
 {
 #if defined(ADCSRB) && defined(MUX5)
-  // the MUX5 bit of ADCSRB selects whether we're reading from channels
-  // 0 to 7 (MUX5 low) or 8 to 15 (MUX5 high).
+  //  the MUX5 bit of ADCSRB selects whether we're reading from channels
+  //  0 to 7 (MUX5 low) or 8 to 15 (MUX5 high).
   ADCSRB = (ADCSRB & ~(1 << MUX5)) | (((_pin >> 3) & 0x01) << MUX5);
 #endif
 
 #if defined(ADMUX)
-  // set the analogue reference (high two bits of ADMUX) and select the
-  // channel (low 4 bits).  this also sets ADLAR (left-adjust result)
-  // to 0 (the default).
+  //  set the analogue reference (high two bits of ADMUX) and select the
+  //  channel (low 4 bits).  this also sets ADLAR (left-adjust result)
+  //  to 0 (the default).
   ADMUX = (DEFAULT << 6) | (_pin & 0x07);
 #endif
 
@@ -45,23 +45,31 @@ void AsyncAnalog::start()
 bool AsyncAnalog::ready()
 {
   // ADSC is cleared when the conversion finishes
-  return bit_is_set(ADCSRA, ADSC) == 0;
+  bool _ready = bit_is_set(ADCSRA, ADSC) == 0;
+
+  if (_ready)  //  calculate the measurement
+  {
+    //  ADCL has to be read first.
+    //  Doing so locks both ADCL and ADCH until ADCH is read.
+    //  Reading ADCL second would cause the results of each conversion to
+    //  be discarded as ADCL and ADCH would be locked when it completed.
+    uint16_t lo = ADCL;
+    uint16_t hi = ADCH;
+    //  Combine two parts.
+    _lastValue = (hi * 256) + lo;
+  }
+  return _ready;
 }
 
 
-int AsyncAnalog::value()
+uint16_t AsyncAnalog::value()
 {
-  //  ADCL has to be read first.
-  //  Doing so locks both ADCL and ADCH until ADCH is read.
-  //  Reading ADCL second would cause the results of each conversion to
-  //  be discarded as ADCL and ADCH would be locked when it completed.
-  uint16_t lo = ADCL;
-  uint16_t hi = ADCH;
-  //  Combine two parts.
-  //  _lastValue = (hi * 256) + lo;
-  return (hi * 256) + lo;
+  return _lastValue;
 }
 
+#else
+
+
 #endif        //  ARDUINO_ARCH_AVR
 
 

AsyncAnalog.h

@@ -2,43 +2,71 @@
 //
 //    FILE: AsyncAnalog.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.6
+// VERSION: 0.2.0
 //    DATE: 2018-09-05
 // PURPOSE: Async version of analogRead for AVR
 //     URL: https://github.com/RobTillaart/AsyncAnalog
 
 
-#if !defined(ARDUINO_ARCH_AVR)
+#define ASYNCANALOG_LIB_VERSION       (F("0.2.0"))
 
-  #error “AsyncAnalog library only supports boards with an AVR processor .”
 
-#else
-
-// (ARDUINO_ARCH_SAM) future
-// (ARDUINO_ARCH_ESP32) future
-// (ARDUINO_ARCH_ESP8266) future
+#if defined(ARDUINO_ARCH_AVR)
 
 
 #include "Arduino.h"
 #include "wiring_private.h"
 #include "pins_arduino.h"
 
-#define ASYNCANALOG_LIB_VERSION       (F("0.1.6"))
-
 
 class AsyncAnalog
 {
 public:
   AsyncAnalog(const uint8_t pin);
 
-  void start();
-  bool ready();
-  int  value();
+  void      start();
+  bool      ready();
+  uint16_t  value();
+
+private:
+  uint8_t  _pin;
+  uint16_t _lastValue;
+};
+
+// #elif defined(ARDUINO_ARCH_SAM)
+// #elif defined(ARDUINO_ARCH_ESP32)
+// #elif defined(ARDUINO_ARCH_ESP8266)
+
+
+#else
+
+#error “AsyncAnalog library only supports boards with an AVR processor .”
+
+
+/*
+#include "Arduino.h"
+
+//  fall back for other platforms?
+
+class AsyncAnalog
+{
+public:
+  AsyncAnalog(const uint8_t pin)
+  {
+    _pin = pin;
+    _lastValue = 0;
+  }
+
+  void      start() { _lastValue = analogRead(_pin); };
+  bool      ready() { return true; };
+  uint16_t  value() { return _lastValue; };
 
 private:
   uint8_t  _pin;
-  //  uint16_t _lastValue;
+  uint16_t _lastValue;
 };
+*/
+
 
 #endif  //  defined(ARDUINO_ARCH_AVR)
 

CHANGELOG.md

@@ -6,12 +6,21 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.2.0] - 2024-04-06
+- change behaviour
+  - cache lastValue as calculated by **ready()**
+- change **uint16_t value()** signature
+- update examples
+- update GitHub actions
+- minor edits
+
+----
+
 ## [0.1.6] - 2023-10-17
 - update readme.md
 - add changelog.md
 - minor edits
 
-
 ## [0.1.5] - 2021-12-13
 - update library.json
 - update license

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2018-2023 Rob Tillaart
+Copyright (c) 2018-2024 Rob Tillaart
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -17,31 +17,41 @@ Arduino Library for async reading of an analogue pin. **\[AVR ONLY\]**.
 ## Description
 
 AsyncAnalog is a library to read the analogue port of an **AVR** in an asynchronous way.
-This means that the user must explicitly **start** the ADC, check if it is **ready**
-and read out its **value**.
+This means that the user must explicitly **start()** the ADC, check if it is **ready()**
+and read its **value()**.
 
 By using this class, the user prevents the (~112 uSec) blocking of the 
 **analogRead()** call, and gives the user the ability to do some processing.
 
 The library works only for AVR boards now, other platforms might be supported in the future.
+(PR's are welcome).
 
 **WARNING**
-As the UNO has only one ADC that is multiplexed, one can only read one analogue pin
-in async way simultaneously.
+As the UNO has only one ADC that is multiplexed, one can only read one analog pin
+in async way simultaneously. Still it offers to about 100 micros to do something!
 
 **Use with care**
 
 
+#### Related
+
+- https://github.com/RobTillaart/AnalogPin
+
+
 ## Interface
 
 ```cpp
 #include "AsynAnalog,h"
 ```
 
 - **AsyncAnalog(uint8_t pin)** constructor, defines the analogue pin to use.
-- **void start()** triggers a new ADC reading.
-- **bool ready()** returns true if sample is complete.
-- **int value()** returns the value.
+- **void start()** triggers a new ADC measurement.
+- **bool ready()** Checks if the measurement is completed. 
+If so the value is calculated and cached for **value()**.
+As long as ready() is not called the old value will not change!
+- **uint16_t value()** returns the value of the ADC from cache.
+So it will return the same value even if the internal ADC is used to sample
+another analog port.
 
 
 ## Operation
@@ -54,18 +64,22 @@ over Serial at 115200 baud.
 
 #### Must
 
+- improve documentation.
+
 #### Should
 
-- improve documentation.
+- create examples
+  - real world examples preferred.
+  - multi ADC, e.g. A0..A4
+
 
 #### Could
 
 - investigate the performance gain.
   - asyncAnalogTest2.ino is not a good test.
-- create examples
-  - real world examples preferred.
 - investigate other platforms
 - fall back to normal analogRead for non AVR platforms ?
+  - start would be analogRead() and it would immediately be ready and the value is cached.
   - better have specific code per platform.
 
 #### Wont

examples/asyncAnalogTest/asyncAnalogTest.ino

@@ -1,8 +1,7 @@
 //
 //    FILE: asyncAnalogTest.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.1
-//    DATE: 2018-09-05
+// PURPOSE: demo
 
 
 #include "AsyncAnalog.h"
@@ -18,9 +17,14 @@ uint16_t count = 0;
 void setup()
 {
   Serial.begin(115200);
-  Serial.println("start: ");
+  Serial.println(__FILE__);
+  Serial.print("ASYNCANALOG_LIB_VERSION: ");
+  Serial.println(ASYNCANALOG_LIB_VERSION);
+
+  Serial.print("\nstart: ");
   Serial.println(analogRead(0));
 
+  //  request initial measurement
   AA.start();
   start = micros();
 }
@@ -29,29 +33,31 @@ void setup()
 void loop()
 {
 
-  // if sample ready 
+  //  if measurement ready
   if (AA.ready())
   {
-    // process sample
+    // get data
     duration = micros() - start;
+    uint16_t val = AA.value();
 
+    //  process measurement
     Serial.print(duration);
-    Serial.print("\t");
-    Serial.print(AA.value());
-    Serial.print("\t");
-    Serial.print(count);
-    Serial.println();
+    Serial.print('\t');
+    Serial.print(val);
+    Serial.print('\t');
+    Serial.println(count);
 
-    // request a new sample
+    //  request a new measurement
     AA.start();
     start = micros();
+
+
     count = 0;
   }
 
-  // do other stuff here
+  //  do other stuff here
   count++;
 }
 
 
-// -- END OF FILE --
-
+//  -- END OF FILE --