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author | Dean Camera <dean@fourwalledcubicle.com> | 2009-02-26 05:48:47 +0000 |
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committer | Dean Camera <dean@fourwalledcubicle.com> | 2009-02-26 05:48:47 +0000 |
commit | 99145a8d7c88d9af065cfb7f5e8507d5b65ff811 (patch) | |
tree | 80b407b9114c1fe6727b40e7b7e0caf6fefc0ea1 /LUFA/GettingStarted.txt | |
parent | fa456ce531b75e2dd3c7c0ecb971e3ede36f5d35 (diff) | |
download | lufa-99145a8d7c88d9af065cfb7f5e8507d5b65ff811.tar.gz lufa-99145a8d7c88d9af065cfb7f5e8507d5b65ff811.tar.bz2 lufa-99145a8d7c88d9af065cfb7f5e8507d5b65ff811.zip |
Makefiles and library modified to add a new F_CLOCK constant to give the unprescaled master input clock frequency, so that the correct PLL mask can be determined even when the CPU (F_CPU) clock rate is prescaled outside the normal input range of the PLL.
Started to clean up the AVRISP Programmer project code, donated by Opendous Inc.
Diffstat (limited to 'LUFA/GettingStarted.txt')
-rw-r--r-- | LUFA/GettingStarted.txt | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/LUFA/GettingStarted.txt b/LUFA/GettingStarted.txt index 0fe3f50b9..a88a82533 100644 --- a/LUFA/GettingStarted.txt +++ b/LUFA/GettingStarted.txt @@ -57,14 +57,22 @@ * directory into a /Board/ folder inside the application directory, and the stub driver completed with the appropriate code to drive the
* custom board's hardware.
*
- * \subsection SSec_F_CPU The F_CPU Parameter
- * This parameter indicates the target AVR's master clock frequency, in Hz. Consult your AVR model's datasheet for allowable clock frequencies
- * if the USB interface is to be operational.
+ * \subsection SSec_F_CLOCK The F_CLOCK Parameter
+ * This parameter indicates the target AVR's input clock frequency, in Hz. This is the actual clock input, before any prescaling is performed. In the
+ * USB AVR architecture, the input clock before any prescaling is fed directly to the PLL subsystem, and thus the PLL is derived directly from the
+ * clock input. The PLL then feeds the USB and other sections of the AVR with the correct upscaled frequencies required for those sections to function.
*
- * <b>Note that this value does not actually *alter* the AVR's clock frequency</b>, it is just a way to indicate to the library the clock frequency
+ * <b>Note that this value does not actually *alter* the AVR's input clock frequency</b>, it is just a way to indicate to the library the clock frequency
* of the AVR as set by the AVR's fuses. If this value does not reflect the actual running frequency of the AVR, incorrect operation of one of more
* library components will ocurr.
*
+ * \subsection SSec_F_CPU The F_CPU Parameter
+ * This parameter indicates the target AVR's master CPU clock frequency, in Hz.
+ *
+ * <b>Note that this value does not actually *alter* the AVR's CPU clock frequency</b>, it is just a way to indicate to the library the clock frequency
+ * of the AVR core as set by the AVR's fuses. If this value does not reflect the actual running frequency of the AVR, incorrect operation of one of more
+ * library components will ocurr.
+ *
* \subsection SSec_CDEFS The CDEFS Parameter
* Most applications will actually have multiple CDEF lines, which are concatenated together with the "+=" operator. This ensures that large
* numbers of configuration options remain readable by splitting up groups of options into seperate lines.
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