0.1.2 MCP3424

Author: RobTillaart

libraries/MCP3424/CHANGELOG.md

@@ -6,6 +6,13 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.1.2] - 2024-10-25
+- fix #4, update readme.md conversion delay
+- fix **setChannel()** optimization
+- add **getConversionDelay()**
+- add example **MCP3428_setChannel.ino**
+- minor edits
+
 ## [0.1.1] - 2024-09-18
 - add derived classes for MCP3421/2/3/6/7/8
 - extend unit tests.

libraries/MCP3424/MCP3424.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: MCP3424.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.1
+// VERSION: 0.1.2
 // PURPOSE: Arduino library for 18 bit ADC I2C MCP3424 and compatibles.
 //     URL: https://github.com/RobTillaart/MCP3424
 
@@ -164,6 +164,14 @@ uint8_t MCP3424::getResolution()
 }
 
 
+uint16_t MCP3424::getConversionDelay()
+{
+  uint16_t  _interval[4] = { 5, 17, 67, 267 };
+  int idx = (_bits - 12) / 2;  //  map 12-> 0 ... 18-> 3
+  return _interval[idx];
+}
+
+
 void MCP3424::setContinuousMode()
 {
   if (getMode() != 1)

libraries/MCP3424/MCP3424.h

@@ -2,15 +2,15 @@
 //
 //    FILE: MCP3424.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.1
+// VERSION: 0.1.2
 // PURPOSE: Arduino library for 18 bit ADC I2C MCP3424 and compatibles.
 //     URL: https://github.com/RobTillaart/MCP3424
 
 
 #include "Arduino.h"
 #include "Wire.h"
 
-#define MCP3424_LIB_VERSION               (F("0.1.1"))
+#define MCP3424_LIB_VERSION               (F("0.1.2"))
 
 
 class MCP3424
@@ -32,12 +32,17 @@ class MCP3424
   float    readMicroVolts();
 
   //  CONFIG
+  //  note that after changing a channel one has to wait before 
+  //       a valid measurement is available, see readme.md.
   bool     setChannel(uint8_t channel = 0);
   uint8_t  getChannel();
   bool     setGain(uint8_t gain = 1);
   uint8_t  getGain();
+
   bool     setResolution(uint8_t bits = 12);
   uint8_t  getResolution();
+  uint16_t getConversionDelay();
+
   //  MODE
   void     setContinuousMode();  //  default
   void     setSingleShotMode();

libraries/MCP3424/README.md

@@ -39,23 +39,31 @@ The user has to configure the ADC device (bits, gain) and can call
 Current implementation will probably change slightly in the future
 when related devices will be supported. (See future section).
 
+As always feedback is welcome.
+
+### Special chars
 
 Alt-230 = µ
 
 
 ### Resolution
 
-|  Bits  |  LSB (gain=1)  |  SPS   |     Raw range       |  Notes  |
-|:------:|---------------:|:------:|:-------------------:|:-------:|
-|   12   |          1 mV  |  240   |    -2048 .. 2047    |
-|   14   |        250 µV  |   60   |    -8192 .. 8191    |
-|   16   |       62.5 µV  |   15   |   -32768 .. 32767   |
-|   18   |     15.625 µV  |  3.75  |  -131072 .. 131071  |  not for 3426/27/28.
+SPS = Samples per second
+
+Interval is the time between consecutive reads in milliseconds. 
+This is also the time to wait after the switching of a channel.
+
+|  Bits  |  LSB (gain=1)  |  SPS   |  Interval  |     Raw range       |  Notes  |
+|:------:|---------------:|:------:|:----------:|:-------------------:|:-------:|
+|   12   |          1 mV  |  240   |    4.2 ms  |    -2048 .. 2047    |
+|   14   |        250 µV  |   60   |   16.7 ms  |    -8192 .. 8191    |
+|   16   |       62.5 µV  |   15   |   66.7 ms  |   -32768 .. 32767   |
+|   18   |     15.625 µV  |  3.75  |  266.7 ms  |  -131072 .. 131071  |  not for 3426/27/28.
 
 The effective resolution also depends on the gain set.
 In theory with a gain of 8 the LSB of the 18 bit resolution represents
 1/8 of 15.625 µV == 1.95 µV.
-If this is feasible in practice is to be seen.
+If this is feasible in practice is to be verified.
 
 
 ### I2C Address
@@ -140,16 +148,32 @@ The user has to configure the ADC device (bits, gain) and can call
 Correct settings will be written to the device immediately, but be aware of the fact
 that it will take some time before the conversion with new settings is done.
 
+#### Channels
+
 - **bool setChannel(uint8_t channel = 0)** not to be used for the MCP3421 as
 it has only one channel. Default is channel 0, parameter should be less than the
 value of **getMaxChannels()**.
+After changing a channel one has to wait an interval depending on the resolution used.
+See table above.
 - **uint8_t getChannel()** returns chosen channel (default 0).
+
+#### Gain
+
 - **bool setGain(uint8_t gain = 1)** set gain to 1,2,4, or 8.
 Other values will return false and not change the setting.
 - **uint8_t getGain()** returns the set gain (default 1).
+
+#### Resolution
+
 - **bool setResolution(uint8_t bits = 12)** set the bit resolution 12,14,16 or 18.
 Other values will return false and not change the setting.
 - **uint8_t getResolution()** returns the set resolution (default 12).
+- **uint16_t getConversionDelay()** returns the delay in ms one has to wait at the
+current resolution between calls to **setChannel()** and /or **read()**.
+See Resolution setcion above.
+
+#### Mode
+
 - **void setContinuousMode()** idem.
 - **void setSingleShotMode()** idem.
 - **uint8_t getMode()** returns 0 for singleShot and 1 for continuous.
@@ -176,7 +200,8 @@ This might be added in the future.
 
 - test on different boards.
 - optimize performance if possible
-- check performance I2C with HW
+  - dividing by ```_gain``` ==> multiplication (faster?).
+- check performance I2C with HW.
 - optimize setting all configuration in one function call.
   - **setConfig(channel, resolution, gain, mode)** ?
   - getter needed?

libraries/MCP3424/examples/MCP3428_setChannel/MCP3428_setChannel.ino

@@ -0,0 +1,64 @@
+//
+//    FILE: MCP3428_setChannel.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: demo to show the needed timeout between setChannel() and read()
+//     URL: https://github.com/RobTillaart/MCP3424
+
+#include "MCP3424.h"
+
+MCP3428 mcp;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("MCP3424_LIB_VERSION: ");
+  Serial.println(MCP3424_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+  Wire.setTimeout(10000);
+
+  mcp.begin();
+
+  //  dump configuration
+  Serial.println();
+  Serial.print("Address:\t");
+  Serial.println(mcp.getAddress(), HEX);
+  Serial.print("Connect:\t");
+  Serial.println(mcp.isConnected());
+  Serial.print("Channels:\t");
+  Serial.println(mcp.getMaxChannels());
+  Serial.print("Gain:\t");
+  Serial.println(mcp.getGain());
+  Serial.print("Bits:\t");
+  Serial.println(mcp.getResolution());
+  Serial.print("Mode:\t");
+  Serial.println(mcp.getMode());
+  Serial.println();
+
+}
+
+
+void loop()
+{
+  uint16_t del = mcp.getConversionDelay();
+
+  //  sample all channels.
+  for (int chan = 0; chan < mcp.getMaxChannels(); chan++)
+  {
+    mcp.setChannel(chan);
+    //  new measurement duration depends on resolution. See readme.md.
+    delay(del);
+    Serial.print(mcp.read());
+    Serial.print("\t");
+    Serial.println(mcp.readVolts(), 6);
+  }
+
+  delay(1000);
+}
+
+
+//  -- END OF FILE --

libraries/MCP3424/keywords.txt

@@ -25,8 +25,10 @@ setChannel	KEYWORD2
 getChannel	KEYWORD2
 setGain	KEYWORD2
 getGain	KEYWORD2
+
 setResolution	KEYWORD2
 getResolution	KEYWORD2
+getConversionDelay	KEYWORD2
 
 setContinuousMode	KEYWORD2
 setSingleShotMode	KEYWORD2

libraries/MCP3424/library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/MCP3424.git"
   },
-  "version": "0.1.1",
+  "version": "0.1.2",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",

libraries/MCP3424/library.properties

@@ -1,5 +1,5 @@
 name=MCP3424
-version=0.1.1
+version=0.1.2
 author=Rob Tillaart <[email protected]>
 maintainer=Rob Tillaart <[email protected]>
 sentence=Arduino library for 18 bit ADC I2C MCP3424 et al.