Fix #12, add buffers to SW I2C (#13)

- add buffers to SW I2C, see issue #12, should fix the SW I2C on AVR.
  - verified with SHT31 on AVR UNO
- minor edits

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/).
 
 
+## [0.3.0] - 2024-05-31
+- add buffers to SW I2C, see issue #12, should fix the SW I2C on AVR.
+  - verified with SHT31 on AVR UNO
+- minor edits
+
+----
+
 ## [0.2.0] - 2023-12-09
 - refactor API, follow SHT31
 

README.md

@@ -34,10 +34,12 @@ devices on one Arduino.
 
 The **SoftWire** library is portable, however it could not read (on AVR)
 the SHT85 sensor which is command compatible with the SHT3x.
-The cause is not found yet.
-Therefore a separate repo is created based upon the AVR specific **SoftwareWire**
+A fix has been made in 0.3.0 and works on AVR (UNO) with an SHT31.
+See #12. It still has to be verified with an SHT85.
+The solution was to add buffers for I2C.
+
+A separate repo is created based upon the AVR specific **SoftwareWire**
 see links below. 
-If you know a solution to get softWire working on AVR, please let me know.
 
 The **SoftwareWire** library is an AVR specific and worked for the SHT85.
 See https://github.com/RobTillaart/SHT31_SW/issues/5
@@ -197,7 +199,8 @@ Returns false if reading fails or in case of a CRC failure.
 #### Should
 
 - remove script for atomic if not needed any more.
-- investigate why SHT85 does not work with SoftWire.
+- verify SHT85 (as SHT31 works now).
+- make **isCOnnected()** more robust, it now only fails on missing CLOCK.
 
 #### Could
 

SHT31_SW.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: SHT31_SW.cpp
 //  AUTHOR: Rob Tillaart, Gunter Haug
-// VERSION: 0.2.0
+// VERSION: 0.3.0
 //    DATE: 2019-02-08 (base SHT31 lib)
 // PURPOSE: Arduino library for the SHT31 temperature and humidity sensor
 //          to be used with the SoftWire library instead of (hardware) Wire.
@@ -36,6 +36,9 @@ bool SHT31_SW::begin()
     return false;
   }
   _softWire->begin();
+  //  See #12
+  _softWire->setTxBuffer(swTxBuffer, sizeof(swTxBuffer));
+  _softWire->setRxBuffer(swRxBuffer, sizeof(swRxBuffer));
   return reset();
 }
 
@@ -63,6 +66,7 @@ bool SHT31_SW::writeCmd(uint16_t cmd)
     _error = SHT31_ERR_WRITECMD;
     return false;
   }
+  //  delay(1);
   return true;
 }
 

SHT31_SW.h

@@ -2,7 +2,7 @@
 //
 //    FILE: SHT31_SW.h
 //  AUTHOR: Rob Tillaart, Gunter Haug
-// VERSION: 0.2.0
+// VERSION: 0.3.0
 //    DATE: 2019-02-08 (base SHT31 lib)
 // PURPOSE: Arduino library for the SHT31 temperature and humidity sensor
 //          to be used with the SoftWire library instead of (hardware) Wire.
@@ -12,7 +12,7 @@
 //          https://github.com/RobTillaart/SHT31
 
 
-#define SHT31_SW_LIB_VERSION             (F("0.2.0"))
+#define SHT31_SW_LIB_VERSION             (F("0.3.0"))
 
 
 #include "Arduino.h"
@@ -32,7 +32,11 @@ class SHT31_SW : public SHT31
 private:
   bool writeCmd(uint16_t cmd);
   bool readBytes(uint8_t n, uint8_t *val);
+
   SoftWire* _softWire;
+
+  char swTxBuffer[8];  //  see #12
+  char swRxBuffer[8];  //  see #12
 };
 
 

examples/SHT31_I2Cspeed/SHT31_I2Cspeed.ino

@@ -38,9 +38,9 @@ void setup()
 
 void loop()
 {
-  for (uint32_t I2Cfreq = 50000; I2Cfreq < 500000; I2Cfreq += 50000)
+  for (uint32_t I2Cfreq = 50000; I2Cfreq <= 400000; I2Cfreq += 50000)
   {
-    Serial.print(I2Cfreq/1000);
+    Serial.print(I2Cfreq / 1000);
     sw.setClock(I2Cfreq);
     test();
   }

examples/SHT31_I2Cspeed/performance_0.3.0.txt

@@ -0,0 +1,22 @@
+
+IDE: 1.8.19
+Board: AVR UNO  -  no speed gain above 300K
+
+SHT31_LIB_VERSION: 	0.3.0
+8010
+50	9912	19.6	64.4
+100	8892	19.5	64.4
+150	8488	19.6	64.3
+200	8300	19.6	64.4
+250	8284	19.5	64.4
+300	8088	19.6	64.5
+350	8092	19.6	64.4
+400	8088	19.6	64.5
+450	8088	19.6	64.4
+500	8088	19.6	64.4
+550	8092	19.6	64.5
+600	8088	19.6	64.4
+650	8088	19.5	64.4
+700	8092	19.7	64.4
+750	8088	19.5	64.4
+800	8096	19.5	64.4

examples/SHT31_demo/SHT31_demo.ino

@@ -11,7 +11,9 @@
 #define SHT31_ADDRESS   0x44
 
 
-SoftWire sw(6, 7);
+// SoftWire sw(32, 33);
+// SoftWire sw(34, 35);
+SoftWire sw(6, 7);  //  sda, scl
 
 uint32_t start;
 uint32_t stop;
@@ -52,7 +54,9 @@ void loop()
   Serial.print("\t");
   Serial.print(sht.getTemperature(), 1);
   Serial.print("\t");
-  Serial.println(sht.getHumidity(), 1);
+  Serial.print(sht.getHumidity(), 1);
+  Serial.print("\t");
+  Serial.println(sht.getError(), HEX);
   delay(3000);
 }
 

examples/SHT31_isConnected/SHT31_isConnected.ino

@@ -3,6 +3,8 @@
 //  AUTHOR: Rob Tillaart
 // PURPOSE: demo
 //     URL: https://github.com/RobTillaart/SHT31_SW
+//
+//  fails only when SCL line is disconnected.
 
 
 #include "SoftWire.h"
@@ -76,4 +78,3 @@ void loop()
 
 
 //  -- END OF FILE --
-

examples/SHT31_rawValues/SHT31_rawValues.ino

@@ -1,5 +1,5 @@
 //
-//    FILE: SHT31_async.ino
+//    FILE: SHT31_rawValues.ino
 //  AUTHOR: Rob Tillaart
 // PURPOSE: demo async interface
 //     URL: https://github.com/RobTillaart/SHT31_SW
@@ -85,4 +85,3 @@ void loop()
 
 
 //  -- END OF FILE --
-

library.json

@@ -31,7 +31,7 @@
       "version": "^1.1.2"
     }
   ],
-  "version": "0.2.0",
+  "version": "0.3.0",
   "license": "MIT",
   "frameworks": "arduino",
   "platforms": "*",

library.properties

@@ -1,5 +1,5 @@
 name=SHT31_SW
-version=0.2.0
+version=0.3.0
 author=Rob Tillaart <rob.tillaart@gmail.com>, Gunter Haug
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for the I2C SHT31 temperature and humidity sensor