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authorpatacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3>2011-06-21 23:53:00 +0000
committerpatacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3>2011-06-21 23:53:00 +0000
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<tr>
<td><br></td>
<td>
+ <p><b>AVR-Specific Issues</b>.
+ The basic AVR port is solid and biggest issue for using AVR is its tiny SRAM memory and its Harvard architecture.
+ Because of the Harvard architecture, constant data that resides to flash is inaccessible using &quot;normal&quot; memory reads and writes (only SRAM data can be accessed &quot;normally&quot;).
+ Special AVR instructions are available for accessing data in FLASH, but these have not been integrated into the normal, general purpose OS.
+ </p>
+ <p>
+ Most NuttX test applications are console-oriented with lots of strings used for printf and debug output.
+ These strings are all stored in SRAM now due to these data accessing issues and even the smallest console-oriented applications can quickly fill a 4-8Kb memory.
+ So, in order for the AVR port to be useful, one of two things would need to be done:
+ </p>
+ <ol>
+ <li>
+ Don't use console applications that required lots of strings.
+ The basic AVR port is solid and your typical deeply embedded application should work fine.
+ Or,
+ </li>
+ <li>
+ Create a special version of printf that knows how to access strings that reside in FLASH (or EEPROM).
+ </li>
+ </ol>
+</tr>
+<tr>
+ <td><br></td>
+ <td>
<p>
<b>Development Environments:</b>
1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain.