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GCC (non)usage of r0
lfmorrison wrote:Hence, it is a scratch register - a function makes the assumption that it is free to modify R0 at any time without any need to save its previous contents ... The...
Tuesday, 22 April 2008 - 17:39
GCC (non)usage of r0
dkinzer wrote:The point that you're missing is that r0 is not available for indiscriminate use in an ISR. If it were, it couldn't be used reliably anywhere else. Go back and...
Tuesday, 22 April 2008 - 16:18
GCC (non)usage of r0
Quote:How does GCC know when the ISR is going to be called?That's a rhetorical question. It doesn't. It's responsible for generating code that can safely be interrupted between...
Monday, 21 April 2008 - 22:54
GCC (non)usage of r0
Well, the ISR prologue is just one of the issues. Presumably that's at least straightforward to change, although adding R0 to the set of registers that are tracked would be more...
Monday, 21 April 2008 - 17:57
GCC (non)usage of r0
And "gcc -S" for mine shows the exact wasteful prologue I described: .text .global __vector_13 .type __vector_13, @function __vector_13: push...
Monday, 21 April 2008 - 10:13
GCC (non)usage of r0
Sure, I've seen docs saying it's used as a scratch register. But that seems to be just docs, and I've not seen any code generated which actually uses it that way. That's my point...
Monday, 21 April 2008 - 09:42
Osscillation frequency of atmega88
Note that there are a couple ways to use external crystals with a Mega88. One is to use a UART-friendly crystal rate like 7.3728 MHz, which divides nicely into 115200 baud....
Sunday, 20 April 2008 - 12:09
AVR chip selection
You actually don't need a dedicated NAND controller to talk to NAND chips ... a parallel I/O port works too. In fact I'm sure I've seen that done on some AVR8 microcontroller, an...
Sunday, 20 April 2008 - 06:26
Problem with multiple SPI devices
Check the specs, compare them to Atmel's similar device. If this is something the chip says it will always do, then see Documentation/SubmittingPatches for more info.
Thursday, 10 April 2008 - 08:05
Problem with multiple SPI devices
Is this behavior guaranteed by the Microchip 25LC010? You might submit a patch for the at25 driver then...
Tuesday, 8 April 2008 - 19:49
i2c slave using AVRLib
By the way, it's probably easier if you structure your code differently: have the I2C IRQ handler issue per-byte callbacks to your code. That way you don't need to pre-allocate...
Tuesday, 1 April 2008 - 05:43
Temperature sensor (ATtinyX4) ... die heats up??
DocJC wrote:Are you building one or many? And, therefore, are you CALIBRATING one, or many? It's set up to use a per-chip offset retrieved from EEPROM, and the chip in the devel...
Monday, 31 March 2008 - 22:02