usbdrv/usbdrvasm165.inc@99a5439f349f
usbdrv/usbdrvasm165.inc
Thu, 16 Feb 2017 16:24:25 +0100
- author
- Malte Di Donato <mdd@neo-soft.org>
- date
- Thu, 16 Feb 2017 16:24:25 +0100
- changeset 4
- 99a5439f349f
- parent 0
- 9e9b2c78bd31
- permissions
- -rw-r--r--
calibration tests added
/* Name: usbdrvasm165.inc * Project: V-USB, virtual USB port for Atmel's(r) AVR(r) microcontrollers * Author: Christian Starkjohann * Creation Date: 2007-04-22 * Tabsize: 4 * Copyright: (c) 2007 by OBJECTIVE DEVELOPMENT Software GmbH * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt) */ /* Do not link this file! Link usbdrvasm.S instead, which includes the * appropriate implementation! */ /* General Description: This file is the 16.5 MHz version of the USB driver. It is intended for the ATTiny45 and similar controllers running on 16.5 MHz internal RC oscillator. This version contains a phase locked loop in the receiver routine to cope with slight clock rate deviations of up to +/- 1%. See usbdrv.h for a description of the entire driver. Since almost all of this code is timing critical, don't change unless you really know what you are doing! Many parts require not only a maximum number of CPU cycles, but even an exact number of cycles! */ ;Software-receiver engine. Strict timing! Don't change unless you can preserve timing! ;interrupt response time: 4 cycles + insn running = 7 max if interrupts always enabled ;max allowable interrupt latency: 59 cycles -> max 52 cycles interrupt disable ;max stack usage: [ret(2), r0, SREG, YL, YH, shift, x1, x2, x3, x4, cnt] = 12 bytes ;nominal frequency: 16.5 MHz -> 11 cycles per bit ; 16.3125 MHz < F_CPU < 16.6875 MHz (+/- 1.1%) ; Numbers in brackets are clocks counted from center of last sync bit ; when instruction starts USB_INTR_VECTOR: ;order of registers pushed: YL, SREG [sofError], r0, YH, shift, x1, x2, x3, x4, cnt push YL ;[-23] push only what is necessary to sync with edge ASAP in YL, SREG ;[-21] push YL ;[-20] ;---------------------------------------------------------------------------- ; Synchronize with sync pattern: ;---------------------------------------------------------------------------- ;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 ;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: inc YL sbis USBIN, USBMINUS 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 ;[-15] rjmp foundK ;[-14] sbis USBIN, USBMINUS rjmp foundK sbis USBIN, USBMINUS rjmp foundK sbis USBIN, USBMINUS rjmp foundK sbis USBIN, USBMINUS rjmp foundK sbis USBIN, USBMINUS rjmp foundK #if USB_COUNT_SOF lds YL, usbSofCount inc YL sts usbSofCount, YL #endif /* USB_COUNT_SOF */ #ifdef USB_SOF_HOOK USB_SOF_HOOK #endif rjmp sofError foundK: ;[-12] ;{3, 5} after falling D- edge, average delay: 4 cycles [we want 5 for center sampling] ;we have 1 bit time for setup purposes, then sample again. Numbers in brackets ;are cycles from center of first sync (double K) bit after the instruction push r0 ;[-12] ; [---] ;[-11] push YH ;[-10] ; [---] ;[-9] lds YL, usbInputBufOffset;[-8] ; [---] ;[-7] clr YH ;[-6] subi YL, lo8(-(usbRxBuf));[-5] [rx loop init] sbci YH, hi8(-(usbRxBuf));[-4] [rx loop init] mov r0, x2 ;[-3] [rx loop init] sbis USBIN, USBMINUS ;[-2] we want two bits K (sample 2 cycles too early) rjmp haveTwoBitsK ;[-1] pop YH ;[0] undo the pushes from before pop r0 ;[2] rjmp waitForK ;[4] this was not the end of sync, retry ; The entire loop from waitForK until rjmp waitForK above must not exceed two ; bit times (= 22 cycles). ;---------------------------------------------------------------------------- ; push more registers and initialize values while we sample the first bits: ;---------------------------------------------------------------------------- haveTwoBitsK: ;[1] push shift ;[1] push x1 ;[3] push x2 ;[5] push x3 ;[7] ldi shift, 0xff ;[9] [rx loop init] ori x3, 0xff ;[10] [rx loop init] == ser x3, clear zero flag in x1, USBIN ;[11] <-- sample bit 0 bst x1, USBMINUS ;[12] bld shift, 0 ;[13] push x4 ;[14] == phase ; [---] ;[15] push cnt ;[16] ; [---] ;[17] ldi phase, 0 ;[18] [rx loop init] ldi cnt, USB_BUFSIZE;[19] [rx loop init] rjmp rxbit1 ;[20] ; [---] ;[21] ;---------------------------------------------------------------------------- ; Receiver loop (numbers in brackets are cycles within byte after instr) ;---------------------------------------------------------------------------- /* byte oriented operations done during loop: bit 0: store data bit 1: SE0 check bit 2: overflow check bit 3: catch up bit 4: rjmp to achieve conditional jump range bit 5: PLL bit 6: catch up bit 7: jump, fixup bitstuff ; 87 [+ 2] cycles ------------------------------------------------------------------ */ continueWithBit5: in x2, USBIN ;[055] <-- bit 5 eor r0, x2 ;[056] or phase, r0 ;[057] sbrc phase, USBMINUS ;[058] lpm ;[059] optional nop3; modifies r0 in phase, USBIN ;[060] <-- phase eor x1, x2 ;[061] bst x1, USBMINUS ;[062] bld shift, 5 ;[063] andi shift, 0x3f ;[064] in x1, USBIN ;[065] <-- bit 6 breq unstuff5 ;[066] *** unstuff escape eor phase, x1 ;[067] eor x2, x1 ;[068] bst x2, USBMINUS ;[069] bld shift, 6 ;[070] didUnstuff6: ;[ ] in r0, USBIN ;[071] <-- phase cpi shift, 0x02 ;[072] brlo unstuff6 ;[073] *** unstuff escape didUnstuff5: ;[ ] nop2 ;[074] ; [---] ;[075] in x2, USBIN ;[076] <-- bit 7 eor x1, x2 ;[077] bst x1, USBMINUS ;[078] bld shift, 7 ;[079] didUnstuff7: ;[ ] eor r0, x2 ;[080] or phase, r0 ;[081] in r0, USBIN ;[082] <-- phase cpi shift, 0x04 ;[083] brsh rxLoop ;[084] ; [---] ;[085] unstuff7: ;[ ] andi x3, ~0x80 ;[085] ori shift, 0x80 ;[086] in x2, USBIN ;[087] <-- sample stuffed bit 7 nop ;[088] rjmp didUnstuff7 ;[089] ; [---] ;[090] ;[080] unstuff5: ;[067] eor phase, x1 ;[068] andi x3, ~0x20 ;[069] ori shift, 0x20 ;[070] in r0, USBIN ;[071] <-- phase mov x2, x1 ;[072] nop ;[073] nop2 ;[074] ; [---] ;[075] in x1, USBIN ;[076] <-- bit 6 eor r0, x1 ;[077] or phase, r0 ;[078] eor x2, x1 ;[079] bst x2, USBMINUS ;[080] bld shift, 6 ;[081] no need to check bitstuffing, we just had one in r0, USBIN ;[082] <-- phase rjmp didUnstuff5 ;[083] ; [---] ;[084] ;[074] unstuff6: ;[074] andi x3, ~0x40 ;[075] in x1, USBIN ;[076] <-- bit 6 again ori shift, 0x40 ;[077] nop2 ;[078] ; [---] ;[079] rjmp didUnstuff6 ;[080] ; [---] ;[081] ;[071] unstuff0: ;[013] eor r0, x2 ;[014] or phase, r0 ;[015] andi x2, USBMASK ;[016] check for SE0 in r0, USBIN ;[017] <-- phase breq didUnstuff0 ;[018] direct jump to se0 would be too long andi x3, ~0x01 ;[019] ori shift, 0x01 ;[020] mov x1, x2 ;[021] mov existing sample in x2, USBIN ;[022] <-- bit 1 again rjmp didUnstuff0 ;[023] ; [---] ;[024] ;[014] unstuff1: ;[024] eor r0, x1 ;[025] or phase, r0 ;[026] andi x3, ~0x02 ;[027] in r0, USBIN ;[028] <-- phase ori shift, 0x02 ;[029] mov x2, x1 ;[030] rjmp didUnstuff1 ;[031] ; [---] ;[032] ;[022] unstuff2: ;[035] eor r0, x2 ;[036] or phase, r0 ;[037] andi x3, ~0x04 ;[038] in r0, USBIN ;[039] <-- phase ori shift, 0x04 ;[040] mov x1, x2 ;[041] rjmp didUnstuff2 ;[042] ; [---] ;[043] ;[033] unstuff3: ;[043] in x2, USBIN ;[044] <-- bit 3 again eor r0, x2 ;[045] or phase, r0 ;[046] andi x3, ~0x08 ;[047] ori shift, 0x08 ;[048] nop ;[049] in r0, USBIN ;[050] <-- phase rjmp didUnstuff3 ;[051] ; [---] ;[052] ;[042] unstuff4: ;[053] andi x3, ~0x10 ;[054] in x1, USBIN ;[055] <-- bit 4 again ori shift, 0x10 ;[056] rjmp didUnstuff4 ;[057] ; [---] ;[058] ;[048] rxLoop: ;[085] eor x3, shift ;[086] reconstruct: x3 is 0 at bit locations we changed, 1 at others in x1, USBIN ;[000] <-- bit 0 st y+, x3 ;[001] ; [---] ;[002] eor r0, x1 ;[003] or phase, r0 ;[004] eor x2, x1 ;[005] in r0, USBIN ;[006] <-- phase ser x3 ;[007] bst x2, USBMINUS ;[008] bld shift, 0 ;[009] andi shift, 0xf9 ;[010] rxbit1: ;[ ] in x2, USBIN ;[011] <-- bit 1 breq unstuff0 ;[012] *** unstuff escape andi x2, USBMASK ;[013] SE0 check for bit 1 didUnstuff0: ;[ ] Z only set if we detected SE0 in bitstuff breq se0 ;[014] eor r0, x2 ;[015] or phase, r0 ;[016] in r0, USBIN ;[017] <-- phase eor x1, x2 ;[018] bst x1, USBMINUS ;[019] bld shift, 1 ;[020] andi shift, 0xf3 ;[021] didUnstuff1: ;[ ] in x1, USBIN ;[022] <-- bit 2 breq unstuff1 ;[023] *** unstuff escape eor r0, x1 ;[024] or phase, r0 ;[025] subi cnt, 1 ;[026] overflow check brcs overflow ;[027] in r0, USBIN ;[028] <-- phase eor x2, x1 ;[029] bst x2, USBMINUS ;[030] bld shift, 2 ;[031] andi shift, 0xe7 ;[032] didUnstuff2: ;[ ] in x2, USBIN ;[033] <-- bit 3 breq unstuff2 ;[034] *** unstuff escape eor r0, x2 ;[035] or phase, r0 ;[036] eor x1, x2 ;[037] bst x1, USBMINUS ;[038] in r0, USBIN ;[039] <-- phase bld shift, 3 ;[040] andi shift, 0xcf ;[041] didUnstuff3: ;[ ] breq unstuff3 ;[042] *** unstuff escape nop ;[043] in x1, USBIN ;[044] <-- bit 4 eor x2, x1 ;[045] bst x2, USBMINUS ;[046] bld shift, 4 ;[047] didUnstuff4: ;[ ] eor r0, x1 ;[048] or phase, r0 ;[049] in r0, USBIN ;[050] <-- phase andi shift, 0x9f ;[051] breq unstuff4 ;[052] *** unstuff escape rjmp continueWithBit5;[053] ; [---] ;[054] macro POP_STANDARD ; 16 cycles pop cnt pop x4 pop x3 pop x2 pop x1 pop shift pop YH pop r0 endm macro POP_RETI ; 5 cycles pop YL out SREG, YL pop YL endm #include "asmcommon.inc" ; USB spec says: ; idle = J ; J = (D+ = 0), (D- = 1) ; K = (D+ = 1), (D- = 0) ; Spec allows 7.5 bit times from EOP to SOP for replies bitstuff7: eor x1, x4 ;[4] ldi x2, 0 ;[5] nop2 ;[6] C is zero (brcc) rjmp didStuff7 ;[8] bitstuffN: eor x1, x4 ;[5] ldi x2, 0 ;[6] lpm ;[7] 3 cycle NOP, modifies r0 out USBOUT, x1 ;[10] <-- out rjmp didStuffN ;[0] #define bitStatus x3 sendNakAndReti: ldi cnt, USBPID_NAK ;[-19] rjmp sendCntAndReti ;[-18] sendAckAndReti: ldi cnt, USBPID_ACK ;[-17] sendCntAndReti: mov r0, cnt ;[-16] ldi YL, 0 ;[-15] R0 address is 0 ldi YH, 0 ;[-14] ldi cnt, 2 ;[-13] ; rjmp usbSendAndReti fallthrough ;usbSend: ;pointer to data in 'Y' ;number of bytes in 'cnt' -- including sync byte [range 2 ... 12] ;uses: x1...x4, shift, cnt, Y ;Numbers in brackets are time since first bit of sync pattern is sent usbSendAndReti: ; 12 cycles until SOP in x2, USBDDR ;[-12] ori x2, USBMASK ;[-11] sbi USBOUT, USBMINUS;[-10] prepare idle state; D+ and D- must have been 0 (no pullups) in x1, USBOUT ;[-8] port mirror for tx loop out USBDDR, x2 ;[-7] <- acquire bus ; need not init x2 (bitstuff history) because sync starts with 0 ldi x4, USBMASK ;[-6] exor mask ldi shift, 0x80 ;[-5] sync byte is first byte sent ldi bitStatus, 0xff ;[-4] init bit loop counter, works for up to 12 bytes byteloop: bitloop: sbrs shift, 0 ;[8] [-3] eor x1, x4 ;[9] [-2] out USBOUT, x1 ;[10] [-1] <-- out ror shift ;[0] ror x2 ;[1] didStuffN: cpi x2, 0xfc ;[2] brcc bitstuffN ;[3] nop ;[4] subi bitStatus, 37 ;[5] 256 / 7 ~=~ 37 brcc bitloop ;[6] when we leave the loop, bitStatus has almost the initial value sbrs shift, 0 ;[7] eor x1, x4 ;[8] ror shift ;[9] didStuff7: out USBOUT, x1 ;[10] <-- out ror x2 ;[0] cpi x2, 0xfc ;[1] brcc bitstuff7 ;[2] ld shift, y+ ;[3] dec cnt ;[5] brne byteloop ;[6] ;make SE0: cbr x1, USBMASK ;[7] prepare SE0 [spec says EOP may be 21 to 25 cycles] lds x2, usbNewDeviceAddr;[8] lsl x2 ;[10] we compare with left shifted address out USBOUT, x1 ;[11] <-- out SE0 -- from now 2 bits = 22 cycles until bus idle ;2006-03-06: moved transfer of new address to usbDeviceAddr from C-Code to asm: ;set address only after data packet was sent, not after handshake subi YL, 2 ;[0] Only assign address on data packets, not ACK/NAK in r0 sbci YH, 0 ;[1] breq skipAddrAssign ;[2] sts usbDeviceAddr, x2; if not skipped: SE0 is one cycle longer skipAddrAssign: ;end of usbDeviceAddress transfer ldi x2, 1<<USB_INTR_PENDING_BIT;[4] int0 occurred during TX -- clear pending flag USB_STORE_PENDING(x2) ;[5] ori x1, USBIDLE ;[6] in x2, USBDDR ;[7] cbr x2, USBMASK ;[8] set both pins to input mov x3, x1 ;[9] cbr x3, USBMASK ;[10] configure no pullup on both pins ldi x4, 4 ;[11] se0Delay: dec x4 ;[12] [15] [18] [21] brne se0Delay ;[13] [16] [19] [22] out USBOUT, x1 ;[23] <-- out J (idle) -- end of SE0 (EOP signal) out USBDDR, x2 ;[24] <-- release bus now out USBOUT, x3 ;[25] <-- ensure no pull-up resistors are active rjmp doReturn
