fix #87, update readme.md about ALERT pulse and polarity

ADS1X15.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: ADS1X15.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.5.1
+// VERSION: 0.5.2
 //    DATE: 2013-03-24
 // PURPOSE: Arduino library for ADS1015 and ADS1115
 //     URL: https://github.com/RobTillaart/ADS1X15

ADS1X15.h

@@ -2,7 +2,7 @@
 //
 //    FILE: ADS1X15.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.5.1
+// VERSION: 0.5.2
 //    DATE: 2013-03-24
 // PURPOSE: Arduino library for ADS1015 and ADS1115
 //     URL: https://github.com/RobTillaart/ADS1X15
@@ -12,7 +12,7 @@
 #include "Arduino.h"
 #include "Wire.h"
 
-#define ADS1X15_LIB_VERSION               (F("0.5.1"))
+#define ADS1X15_LIB_VERSION               (F("0.5.2"))
 
 //  allow compile time default address
 //  address in { 0x48, 0x49, 0x4A, 0x4B }, no test...

CHANGELOG.md

@@ -5,6 +5,11 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.5.2] - 2025-01-27
+- Add note about falling edge when using interrupts, see #87
+- update comments in some examples
+- minor edits 
+
 ## [0.5.1] - 2024-10-17
 - fix #82, minimal timeout 10 ms for RTOS, kudos to deKees687 
 - set error flag for TIMEOUT

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2013-2024 Rob Tillaart
+Copyright (c) 2013-2025 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

@@ -39,7 +39,7 @@ differential measurements.
 
 ### Interrupts
 
-Besides polling the ADS1x14 and ADS1x15 support interrupts to maximize throughput 
+Besides polling the **ADS1x14** and **ADS1x15** support interrupts to maximize throughput 
 with minimal latency. For this these device has an ALERT/RDY pin. 
 This pin can be used both for interrupts or polling, see table of examples below.
 
@@ -55,6 +55,19 @@ This pin can be used both for interrupts or polling, see table of examples below
 |  ADS_read_RDY.ino                 |   polling    |
 
 
+The examples of this library all use the **RISING** edge for the interrupt detection
+of the ALERT / RDY pin. 
+In https://github.com/RobTillaart/ADS1X15/issues/87 it is observed that the **FALLING** 
+edge gave far more stable results for the application used (determine True RMS). 
+This effect can not be explained as the edges are only 8 us apart.
+Thus changing the edge to **FALLING** might improve your measurements too.
+
+Datasheet section 7.3.8 Conversion ready pin, figure 7-8 indicates using 
+the **FALLING** edge as the moment the conversion is ready.
+
+If anybody can explain the observed effect, please let me know.
+
+
 ### 0.5.0 Breaking change
 
 Fixed #80, setComparatorPolarity() and setComparatorLatch() as these inverted
@@ -72,12 +85,14 @@ before calling **begin()**.
 
 ### Related
 
+- https://github.com/RobTillaart/AD7367 2 channel simultaneous 14 bit ADC.
 - https://github.com/RobTillaart/ADC081S 10-12 bit, single channel ADC
 - https://github.com/RobTillaart/ADC08XS 10-12 bit, 2 + 4 channel ADC
 - https://gammon.com.au/adc tutorial about ADC's (UNO specific)
 - https://github.com/RobTillaart/MCP_ADC 10-12 bit, 1,2,4,8 channel ADC
 - https://github.com/RobTillaart/ADS1x15
 - https://github.com/RobTillaart/PCF8591 8 bit single ADC (+ 1 bit DAC)
+- https://github.com/RobTillaart/AD5593R 8 channel ADC / DAC / GPIO device.
 
 
 ## I2C Address
@@ -284,7 +299,7 @@ Therefore the user should check with **getError()** if an error has occurred aft
       //  handle error
 ```
 
-The errorhandling within the library need to be improved, see also issue #84.
+The error handling within the library need to be improved, see also issue #84.
 
 
 ### Read the ADC in asynchronous way
@@ -511,15 +526,17 @@ as that is the only single change visible. This is IMHO the correct view.
 
 #### ALERT RDY table
 
-|  MODE          |  COMP_POL  |  IDLE  |  START    |  CONVERT  |   READY   |
-|:---------------|:-----------|:-------|:----------|:----------|:----------|
-| 0 = continuous |  0 = LOW   |  HIGH  |  FALLING  |  LOW      |  RISING   |
-| 0 = continuous |  1 = HIGH  |  LOW   |  RISING   |  HIGH     |  FALLING  |
-| 1 = single     |  0 = LOW   |  HIGH  |  FALLING  |  LOW      |  RISING   |
-| 1 = single     |  1 = HIGH  |  LOW   |  RISING   |  HIGH     |  FALLING  |
+|  MODE          |  COMP_POL  |  CONVERT  |  COMPLETING  |   READY   |
+|:---------------|:-----------|:----------|:-------------|:----------|
+| 0 = continuous |  0 = LOW   |  LOW      |   RISING     |  FALLING  |
+| 0 = continuous |  1 = HIGH  |  HIGH     |   FALLING    |  RISING   |
+| 1 = single     |  0 = LOW   |  LOW      |   RISING     |  FALLING  |
+| 1 = single     |  1 = HIGH  |  HIGH     |   FALLING    |  RISING   |
+
 
+See issue #76 and #87 for some screenshots.
 
-See issue #76 for some screenshots.
+See also [Rev. D data sheet, Page 17 Figure 7-8 Conversion Ready Pulse in Continuous-Conversion Mode](https://www.ti.com/lit/ds/symlink/ads1115.pdf)
 
 
 #### Converting time by Data Rate
@@ -547,18 +564,18 @@ Times are estimates from scope.
 In short:
 
 - if COMP_POL = 0, 
-  - a FALLING edge indicates conversion start.
   - a LOW level indicates converting.
-  - a RISING edge indicates conversion ready.
-  - a HIGH level indicates idle.
- 
+  - a RISING edge indicates conversion completing.
+  - a FALLING edge indicates conversion ready.
+
 - if COMP_POL = 1, 
-  - a RISING edge indicates conversion start.
   - a HIGH level indicates converting.
-  - a FALLING edge indicates conversion ready.
-  - a LOW level indicates idle.
+  - a FALLING edge indicates conversion completing.
+  - a RISING edge indicates conversion ready.
+
+This interpretation is in line with all tests done in #76 and #87.
 
-This interpretation is in line with all tests done in #76.
+See also [Rev. D data sheet, Page 17 Figure 7-8 Conversion Ready Pulse in Continuous-Conversion Mode](https://www.ti.com/lit/ds/symlink/ads1115.pdf)
 
 
 ### Latch

examples/ADS_1114_two_continuous/ADS_1114_two_continuous.ino

@@ -2,8 +2,27 @@
 //    FILE: ADS_1114_two_continuous.ino
 //  AUTHOR: Rob.Tillaart
 // PURPOSE: demo reading four ADS1114 modules in parallel
+//          interrupt driven to catch all conversions.
 //     URL: https://github.com/RobTillaart/ADS1X15
 
+//  test
+//  connect multiple potmeters to 2 ADS1114
+//
+//
+//  RDY1 ----------------- pin 2 (for IRQ, adjust if needed)
+//
+//  RDY2 ----------------- pin 3 (for IRQ, adjust if needed)
+//
+//
+//  GND ---[   x   ]------ 5V
+//             |
+//
+//  measure at x  - connect to AIN0..1.
+//
+//  for the test it is good to have AIN2 connected to 5V and AIN3 to GND
+//  so one can see these as references in the output.
+//
+
 
 #include "ADS1X15.h"
 
@@ -61,8 +80,8 @@ void setup()
   pinMode(3, INPUT_PULLUP);
   attachInterrupt(digitalPinToInterrupt(3), adsReady_2, RISING);
 
-  ADS_2.setMode(0);         //  0 == continuous mode
-  ADS_2.readADC();          //  0 == default channel,  trigger first read
+  ADS_2.setMode(0);          //  0 == continuous mode
+  ADS_2.readADC();           //  0 == default channel,  trigger first read
 }
 
 

examples/ADS_continuous_3_channel/ADS_continuous_3_channel.ino

@@ -11,16 +11,16 @@
 //  test
 //  connect multiple potmeters
 //
-//  RDY ----------------- pin 2 (for IRQ)
+//  RDY ----------------- pin 2 (for IRQ, adjust if needed)
 //
 //  GND ---[   x   ]------ 5V
 //             |
 //             |
 //           ADS(n)
 //
-//  measure at x  - connect to AIN0..3.
+//  measure at x  - connect to AIN0..1.
 //
-//  for the test it is an option to have AIN3 connected to 5V and AIN4 to GND
+//  for the test it is an option to have AIN2 connected to 5V and AIN3 to GND
 //  so one can see these as references in the output.
 //
 //  has an issue with the index of the channels. not not investigated yet.

examples/ADS_continuous_4_channel/ADS_continuous_4_channel.ino

@@ -8,12 +8,14 @@
 //  test
 //  connect multiple potmeters
 //
+//  RDY ----------------- pin 2 (for IRQ, adjust if needed)
+//
 //  GND ---[   x   ]------ 5V
 //             |
 //
-//  measure at x  - connect to AIN0..4.
+//  measure at x  - connect to AIN0..1.
 //
-//  for the test it is good to have AIN3 connected to 5V and AIN4 to GND
+//  for the test it is good to have AIN2 connected to 5V and AIN3 to GND
 //  so one can see these as references in the output.
 //
 

examples/ADS_continuous_8_channel/ADS_continuous_8_channel.ino

@@ -8,12 +8,18 @@
 //  test
 //  connect multiple potmeters to 2 ADS1115
 //
+//
+//  RDY1 ----------------- pin 2 (for IRQ, adjust if needed)
+//
+//  RDY2 ----------------- pin 3 (for IRQ, adjust if needed)
+//
+//
 //  GND ---[   x   ]------ 5V
 //             |
 //
-//  measure at x  - connect to AIN0..4.
+//  measure at x  - connect to AIN0..1.
 //
-//  for the test it is good to have AIN3 connected to 5V and AIN4 to GND
+//  for the test it is good to have AIN2 connected to 5V and AIN3 to GND
 //  so one can see these as references in the output.
 //
 
@@ -47,8 +53,8 @@ void setup()
 
   //  SETUP FIRST ADS1115
   ADS_1.begin();
-  ADS_1.setGain(0);        //  6.144 volt
-  ADS_1.setDataRate(7);    //  0 = slow   4 = medium   7 = fast
+  ADS_1.setGain(0);         //  0 == 6.144 volt, default
+  ADS_1.setDataRate(7);     //  0 = slow   4 = medium   7 = fast
 
   //  SET ALERT RDY PIN
   ADS_1.setComparatorThresholdHigh(0x8000);
@@ -59,14 +65,14 @@ void setup()
   pinMode(2, INPUT_PULLUP);
   attachInterrupt(digitalPinToInterrupt(2), adsReady_1, RISING);
 
-  ADS_1.setMode(0);          //  continuous mode
-  ADS_1.readADC(channel_1);  //  trigger first read
+  ADS_1.setMode(0);         //  0 == continuous mode
+  ADS_1.readADC(channel_1); //  0 == default channel,  trigger first read
 
 
   //  SETUP SECOND ADS1115
   ADS_2.begin();
-  ADS_2.setGain(0);          //  6.144 volt
-  ADS_2.setDataRate(7);
+  ADS_2.setGain(0);         //  0 == 6.144 volt, default
+  ADS_2.setDataRate(7);     //  7 == highest
 
   //  SET ALERT RDY PIN
   ADS_2.setComparatorThresholdHigh(0x8000);
@@ -77,8 +83,8 @@ void setup()
   pinMode(3, INPUT_PULLUP);
   attachInterrupt(digitalPinToInterrupt(3), adsReady_2, RISING);
 
-  ADS_2.setMode(0);          //  continuous mode
-  ADS_2.readADC(channel_2);  //  trigger first read
+  ADS_2.setMode(0);          //  0 == continuous mode
+  ADS_2.readADC(channel_2);  //  0 == default channel,  trigger first read
 }
 
 

examples/ADS_continuous_differential/ADS_continuous_differential.ino

@@ -7,11 +7,14 @@
 //  test
 //  connect 4 potmeters
 //
+//  RDY ----------------- pin 2 (for IRQ, adjust if needed)
+//
 //  GND ---[   x   ]------ 5V
 //             |
 //
-//  measure at x  - connect to AIN0..4.
+//  measure at x  - connect to AIN0..3.
 //
+//  adjust IRQ pin if needed
 
 
 #include "ADS1X15.h"

library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/ADS1X15"
   },
-  "version": "0.5.1",
+  "version": "0.5.2",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",

library.properties

@@ -1,5 +1,5 @@
 name=ADS1X15
-version=0.5.1
+version=0.5.2
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for ADS1015 - I2C 12 bit ADC and ADS1115 I2C 16 bit ADC