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| author | Christian Starkjohann <cs+github@obdev.at> | 2008-10-20 13:18:39 +0000 |
|---|---|---|
| committer | Christian Starkjohann <cs+github@obdev.at> | 2008-10-20 13:18:39 +0000 |
| commit | aacf677a758f61f273ab8dff5c8a6a92eee4404a (patch) | |
| tree | c5598e6b6d5a887f1d08f31a5ff930a1f058e8be /usbdrv/usbdrvasm12.inc | |
| parent | 232152349a0a601dd67581850fd08e108867d250 (diff) | |
| download | v-usb-aacf677a758f61f273ab8dff5c8a6a92eee4404a.tar.gz v-usb-aacf677a758f61f273ab8dff5c8a6a92eee4404a.tar.bz2 v-usb-aacf677a758f61f273ab8dff5c8a6a92eee4404a.zip | |
- use timeout in waitForJ
Diffstat (limited to 'usbdrv/usbdrvasm12.inc')
| -rw-r--r-- | usbdrv/usbdrvasm12.inc | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/usbdrv/usbdrvasm12.inc b/usbdrv/usbdrvasm12.inc index d9da1dc..f891ab6 100644 --- a/usbdrv/usbdrvasm12.inc +++ b/usbdrv/usbdrvasm12.inc @@ -48,10 +48,14 @@ USB_INTR_VECTOR: ;---------------------------------------------------------------------------- ;sync byte (D-) pattern LSb to MSb: 01010100 [1 = idle = J, 0 = K] ;sync up with J to K edge during sync pattern -- use fastest possible loops -;first part has no timeout because it waits for IDLE or SE1 (== disconnected) +;The first part waits at most 1 bit long since we must be in sync pattern. +;YL is guarenteed to be < 0x80 because I flag is clear. When we jump to +;waitForJ, ensure that this prerequisite is met. waitForJ: - sbis USBIN, USBMINUS ;1 [40] wait for D- == 1 - rjmp waitForJ ;2 + sbic USBIN, USBMINUS + rjmp waitForK + inc YL + brne waitForJ ; just make sure we have ANY timeout waitForK: ;The following code results in a sampling window of 1/4 bit which meets the spec. sbis USBIN, USBMINUS |