Begin work to convert embedded-creations USBaspLoader-tiny85 port to bootloadHID

1 files changed, 88 insertions, 0 deletions

diff --git a/firmware/libs-device/osctune.h b/firmware/libs-device/osctune.h
new file mode 100644
index 0000000..c751648
--- /dev/null
+++ b/firmware/libs-device/osctune.h
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+/* Name: osctune.h
+ * Author: Christian Starkjohann
+ * Creation Date: 2008-10-18
+ * Tabsize: 4
+ * Copyright: (c) 2008 by OBJECTIVE DEVELOPMENT Software GmbH
+ * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt)
+ * This Revision: $Id: osctune.h 692 2008-11-07 15:07:40Z cs $
+ */
+
+/*
+General Description:
+This file is declared as C-header file although it is mostly documentation
+how the RC oscillator can be kept in sync to the USB frame rate. The code
+shown here must be added to usbconfig.h or this header file is included from
+there. This code works only if D- is wired to the interrupt, not D+!!!
+
+This is an alternative to the osccal routine in osccal.c. It has the advantage
+that the synchronization is done continuously and that it has more compact
+code size. The disadvantages are slow synchronization (it may take a while
+until the driver works), that messages immediately after the SOF pulse may be
+lost (and need to be retried by the host) and that the interrupt is on D-
+contrary to most examples.
+
+You may want to store a good calibration value in EEPROM for the next startup.
+You know that the calibration value is good when the first USB message is
+received. Do not store the value on every received message because the EEPROM
+has a limited endurance.
+
+Notes:
+(*) You must declare the global character variable "lastTimer0Value" in your
+main code.
+
+(*) Timer 0 must be free running (not written by your code) and the prescaling
+must be consistent with the TIMER0_PRESCALING define.
+
+(*) Good values for Timer 0 prescaling depend on how precise the clock must
+be tuned and how far away from the default clock rate the target clock is.
+For precise tuning, choose a low prescaler factor, for a broad range of tuning
+choose a high one. A prescaler factor of 64 is good for the entire OSCCAL
+range and allows a precision of better than +/-1%. A prescaler factor of 8
+allows tuning to slightly more than +/-6% of the default frequency and is
+more precise than one step of OSCCAL. It is therefore not suitable to tune an
+8 MHz oscillator to 12.5 MHz.
+
+Thanks to Henrik Haftmann for the idea to this routine!
+*/
+
+#define TIMER0_PRESCALING           64 /* must match the configuration for TIMER0 in main */
+#define TOLERATED_DEVIATION_PPT     5  /* max clock deviation before we tune in 1/10 % */
+/* derived constants: */
+#define EXPECTED_TIMER0_INCREMENT   ((F_CPU / (1000 * TIMER0_PRESCALING)) & 0xff)
+#define TOLERATED_DEVIATION         (TOLERATED_DEVIATION_PPT * F_CPU / (1000000 * TIMER0_PRESCALING))
+
+#ifdef __ASSEMBLER__
+macro tuneOsccal
+    push    YH                              ;[0]
+    in      YL, TCNT0                       ;[2]
+    lds     YH, lastTimer0Value             ;[3]
+    sts     lastTimer0Value, YL             ;[5]
+    sub     YL, YH                          ;[7] time passed since last frame
+    subi    YL, EXPECTED_TIMER0_INCREMENT   ;[8]
+#if OSCCAL > 0x3f   /* outside I/O addressable range */
+    lds     YH, OSCCAL                      ;[6]
+#else
+    in      YH, OSCCAL                      ;[6] assembler modle uses __SFR_OFFSET == 0
+#endif
+    cpi     YL, TOLERATED_DEVIATION + 1     ;[10]
+    brmi    notTooHigh                      ;[11]
+    subi    YH, 1                           ;[12] clock rate was too high
+;   brcs    tuningOverflow                  ; optionally check for overflow
+    rjmp    osctuneDone                     ;[13]
+notTooHigh:
+    cpi     YL, -TOLERATED_DEVIATION        ;[13]
+    brpl    osctuneDone                     ;[14] not too low
+    inc     YH                              ;[15] clock rate was too low
+;   breq    tuningOverflow                  ; optionally check for overflow
+osctuneDone:
+#if OSCCAL > 0x3f   /* outside I/O addressable range */
+    sts     OSCCAL, YH                      ;[12-13] store tuned value
+#else
+    out     OSCCAL, YH                      ;[12-13] store tuned value
+#endif
+tuningOverflow:
+    pop     YH                              ;[17]
+    endm                                    ;[19] max number of cycles
+#endif
+
+#define USB_SOF_HOOK        tuneOsccal