add determineSizeNoWrite() (#62)

- add **uint32_t determineSizeNoWrite()**, kudos to roelandkluit
- add example
- minor edits

CHANGELOG.md

@@ -6,12 +6,19 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [1.8.1] - 2023-12-14
+- add **uint32_t determineSizeNoWrite()**, kudos to roelandkluit
+- add example
+- minor edits
+
+
 ## [1.8.0] - 2023-11-24  (breaking change)
 - simplify **begin()**, remove setting Wire pins from library.
 - add **getAddress()**
 - update readme.md
 - update examples
 
+----
 
 ## [1.7.4] - 2023-09-06
 - solve #57 add support for WriteProtectPin

I2C_eeprom.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: I2C_eeprom.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 1.8.0
+// VERSION: 1.8.1
 // PURPOSE: Arduino Library for external I2C EEPROM 24LC256 et al.
 //     URL: https://github.com/RobTillaart/I2C_EEPROM.git
 
@@ -304,33 +304,36 @@ uint32_t I2C_eeprom::determineSize(const bool debug)
   return 0;
 }
 
+
+//  new 1.8.1 #61
 uint32_t I2C_eeprom::determineSizeNoWrite()
 {
-    // try to read a byte to see if connected
-    if (!isConnected()) return 0;
+  //  try to read a byte to see if connected
+  if (!isConnected()) return 0;
 
-    bool addressSize = _isAddressSizeTwoWords;
-    byte dummyVal = 0;
-    uint32_t lastOkSize = 0;
+  bool addressSize = _isAddressSizeTwoWords;
+  byte dummyVal = 0;
+  uint32_t lastOkSize = 0;
+
+  for (uint32_t size = 128; size <= 65536; size *= 2)
+  {
+    _isAddressSizeTwoWords = (size > I2C_DEVICESIZE_24LC16);  //  == 2048
 
-    for (uint32_t size = 128; size <= 65536; size *= 2)
+    //  Try to read last byte of the block, should return length of 0 when fails
+    if (readBlock(size - 1, &dummyVal, 1) == 0)
     {
-        _isAddressSizeTwoWords = size > I2C_DEVICESIZE_24LC16;  // 2048
-
-        //Try to read last byte of the block, should return lenght of 0 when fails
-        if (readBlock(size - 1, &dummyVal, 1) == 0)
-        {
-            _isAddressSizeTwoWords = addressSize;
-            break;
-        }
-        else
-        {
-            lastOkSize = size;
-        }
+      _isAddressSizeTwoWords = addressSize;
+      break;
     }
-    return lastOkSize;
+    else
+    {
+      lastOkSize = size;
+    }
+  }
+  return lastOkSize;
 }
 
+
 uint32_t I2C_eeprom::getDeviceSize()
 {
   return _deviceSize;

I2C_eeprom.h

@@ -2,7 +2,7 @@
 //
 //    FILE: I2C_eeprom.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 1.8.0
+// VERSION: 1.8.1
 // PURPOSE: Arduino Library for external I2C EEPROM 24LC256 et al.
 //     URL: https://github.com/RobTillaart/I2C_EEPROM.git
 

README.md

@@ -139,6 +139,8 @@ Same as write and update functions above. Returns true if successful, false indi
 - **uint8_t  getPageSize()** idem
 - **uint8_t  getPageSize(uint32_t deviceSize)** idem
 - **uint32_t getLastWrite()** idem
+- **uint32_t determineSizeNoWrite()** function that determines the size of the EEPROM 
+by detecting when a selected memory address is not readable. (new in 1.8.1).
 - **uint32_t determineSize(bool debug = false)**
 function that determines the size of the EEPROM by detecting when a memory address 
 is folded upon memory address 0.
@@ -147,7 +149,7 @@ The debug flag prints some output to Serial.
 
 **Warning**: this function has changed (again) in 1.4.0
 
-Test results
+Test results **determineSize()**
 
 | Type    | returns |  Memory  | Page Size | Notes |
 |:--------|:--------|:---------|:---------:|:------|

examples/I2C_eeprom_determineSizeNoWrite/I2C_eeprom_determineSizeNoWrite.ino

@@ -0,0 +1,73 @@
+//
+//    FILE: I2C_eeprom_determineSizeNoWrite.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: test determineSizeNoWrite() function
+
+
+#include "Wire.h"
+#include "I2C_eeprom.h"
+
+
+I2C_eeprom ee(0x50, I2C_DEVICESIZE_24LC256);
+
+uint32_t start, diff;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while (!Serial);  //  wait for Serial port to connect. Needed for Leonardo only
+  Serial.println(__FILE__);
+  Serial.print("I2C_EEPROM_VERSION: ");
+  Serial.println(I2C_EEPROM_VERSION);
+
+  Wire.begin();
+
+  ee.begin();
+  if (! ee.isConnected())
+  {
+    Serial.println("ERROR: Can't find eeprom\nstopped...");
+    while (1);
+  }
+
+  Serial.println("\nDetermine size no write");
+  delay(100);
+
+  start = micros();
+  uint32_t size = ee.determineSizeNoWrite();
+  diff = micros() - start;
+  Serial.print("TIME: ");
+  Serial.print(diff);
+  Serial.println(" us.");
+  if (size == 0)
+  {
+    Serial.println("SIZE: could not determine size");
+  }
+  else if (size > 1024)
+  {
+    Serial.print("SIZE: ");
+    Serial.print(size / 1024);
+    Serial.println(" KB.");
+  }
+  else
+  {
+    Serial.print("SIZE: ");
+    Serial.print(size);
+    Serial.println(" bytes.");
+  }
+
+  Serial.print("PAGE: ");
+  uint8_t pageSize = ee.getPageSize(size);
+  Serial.print(pageSize);
+  Serial.println(" bytes.");
+
+  Serial.println("Done...");
+}
+
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --

keywords.txt

@@ -30,6 +30,7 @@ updateByteVerify	KEYWORD2
 updateBlockVerify	KEYWORD2
 
 determineSize	KEYWORD2
+determineSizeNoWrite	KEYWORD2
 getDeviceSize	KEYWORD2
 getPageSize	KEYWORD2
 getLastWrite	KEYWORD2

library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/I2C_EEPROM.git"
   },
-  "version": "1.8.0",
+  "version": "1.8.1",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",