diff options
Diffstat (limited to 'libraries')
4 files changed, 94 insertions, 31 deletions
diff --git a/libraries/EEPROM/examples/eeprom_clear/eeprom_clear.ino b/libraries/EEPROM/examples/eeprom_clear/eeprom_clear.ino index b18ff2c..49eb5fe 100644 --- a/libraries/EEPROM/examples/eeprom_clear/eeprom_clear.ino +++ b/libraries/EEPROM/examples/eeprom_clear/eeprom_clear.ino @@ -2,22 +2,34 @@ * EEPROM Clear * * Sets all of the bytes of the EEPROM to 0. + * Please see eeprom_iteration for a more in depth + * look at how to traverse the EEPROM. + * * This example code is in the public domain. - */ #include <EEPROM.h> void setup() { - // write a 0 to all 512 bytes of the EEPROM - for (int i = 0; i < 512; i++) + + /*** + Iterate through each byte of the EEPROM storage. + + Larger AVR processors have larger EEPROM sizes, E.g: + - Arduno Duemilanove: 512b EEPROM storage. + - Arduino Uno: 1kb EEPROM storage. + - Arduino Mega: 4kb EEPROM storage. + + Rather than hard-coding the length, you should use the pre-provided length function. + This will make your code portable to all AVR processors. + ***/ + + for ( int i = 0 ; i < EEPROM.length() ; i++ ) EEPROM.write(i, 0); // turn the LED on when we're done digitalWrite(13, HIGH); } -void loop() -{ -} +void loop(){ /** Empty loop. **/ } diff --git a/libraries/EEPROM/examples/eeprom_read/eeprom_read.ino b/libraries/EEPROM/examples/eeprom_read/eeprom_read.ino index ebf79d6..8567ed7 100644 --- a/libraries/EEPROM/examples/eeprom_read/eeprom_read.ino +++ b/libraries/EEPROM/examples/eeprom_read/eeprom_read.ino @@ -31,13 +31,27 @@ void loop() Serial.print(value, DEC); Serial.println(); - // advance to the next address of the EEPROM - address = address + 1; - - // there are only 512 bytes of EEPROM, from 0 to 511, so if we're - // on address 512, wrap around to address 0 - if (address == 512) - address = 0; + /*** + Advance to the next address, when at the end restart at the beginning. + + Larger AVR processors have larger EEPROM sizes, E.g: + - Arduno Duemilanove: 512b EEPROM storage. + - Arduino Uno: 1kb EEPROM storage. + - Arduino Mega: 4kb EEPROM storage. + + Rather than hard-coding the length, you should use the pre-provided length function. + This will make your code portable to all AVR processors. + ***/ + addr = addr + 1; + if(addr == EEPROM.length()) + addr = 0; + + /*** + As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an + EEPROM address is also doable by a bitwise and of the length - 1. + + ++addr &= EEPROM.length() - 1; + ***/ delay(500); } diff --git a/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino b/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino index e0e18d8..dbf05ec 100644 --- a/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino +++ b/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino @@ -38,15 +38,32 @@ void loop() The function EEPROM.update(addr, val) is equivalent to the following: if( EEPROM.read(addr) != val ){ - EEPROM.write(addr, val); + EEPROM.write(addr, val); } ***/ - /** advance to the next address. there are 512 bytes in the EEPROM, so go back to 0 when we hit 512. **/ + /*** + Advance to the next address, when at the end restart at the beginning. + + Larger AVR processors have larger EEPROM sizes, E.g: + - Arduno Duemilanove: 512b EEPROM storage. + - Arduino Uno: 1kb EEPROM storage. + - Arduino Mega: 4kb EEPROM storage. + + Rather than hard-coding the length, you should use the pre-provided length function. + This will make your code portable to all AVR processors. + ***/ addr = addr + 1; - if (addr == 512) + if(addr == EEPROM.length()) addr = 0; + + /*** + As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an + EEPROM address is also doable by a bitwise and of the length - 1. + + ++addr &= EEPROM.length() - 1; + ***/ delay(100); } diff --git a/libraries/EEPROM/examples/eeprom_write/eeprom_write.ino b/libraries/EEPROM/examples/eeprom_write/eeprom_write.ino index c047887..f07446c 100644 --- a/libraries/EEPROM/examples/eeprom_write/eeprom_write.ino +++ b/libraries/EEPROM/examples/eeprom_write/eeprom_write.ino @@ -8,31 +8,51 @@ #include <EEPROM.h> -// the current address in the EEPROM (i.e. which byte -// we're going to write to next) -int addr = 0; +/** the current address in the EEPROM (i.e. which byte we're going to write to next) **/ +int addr = 0; -void setup() -{ -} +void setup(){ /** Empty setup. **/} void loop() { - // need to divide by 4 because analog inputs range from - // 0 to 1023 and each byte of the EEPROM can only hold a - // value from 0 to 255. + /*** + Need to divide by 4 because analog inputs range from + 0 to 1023 and each byte of the EEPROM can only hold a + value from 0 to 255. + ***/ + int val = analogRead(0) / 4; - // write the value to the appropriate byte of the EEPROM. - // these values will remain there when the board is - // turned off. + /*** + Write the value to the appropriate byte of the EEPROM. + these values will remain there when the board is + turned off. + ***/ + EEPROM.write(addr, val); - // advance to the next address. there are 512 bytes in - // the EEPROM, so go back to 0 when we hit 512. + /*** + Advance to the next address, when at the end restart at the beginning. + + Larger AVR processors have larger EEPROM sizes, E.g: + - Arduno Duemilanove: 512b EEPROM storage. + - Arduino Uno: 1kb EEPROM storage. + - Arduino Mega: 4kb EEPROM storage. + + Rather than hard-coding the length, you should use the pre-provided length function. + This will make your code portable to all AVR processors. + ***/ addr = addr + 1; - if (addr == 512) + if(addr == EEPROM.length()) addr = 0; + + /*** + As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an + EEPROM address is also doable by a bitwise and of the length - 1. + + ++addr &= EEPROM.length() - 1; + ***/ + delay(100); } |