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view notes/cdd_mcu_notes.txt @ 2437:79a8cccb6ac1
Add region override for German version of The Lion King for Pico
author | Michael Pavone <pavone@retrodev.com> |
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date | Sat, 10 Feb 2024 17:46:30 -0800 |
parents | f1c2415f4d1d |
children |
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CD Block Clock: 16.9344 MHz MCU Clock divider: 2.1168 MHz (cd clock / 8) State at Reset: Status buffer is filled with zero Mechanism is reset Emulation state set to ES_CLOSING HSCK active low IRQ active high CDCK active high Main Loop: wait for subcode data for next frame seems to be delivered via a "bank" IRQ if servo is not in PLAY state set DOUT and EMP to inactive set MUTE to active elif Q subcode CRC is not valid set MUTE to active elif Q subcode CONTROL field indicates a DATA track set DOUT and MUTE to active set EMP to inactive else set DOUT and MUTE to inactive set EMP based on emphasis bit in Q subcode CONTROL field run drive emulation state machine if we received a valid command last loop populate status buffer based on request format (see table below) if drive error status is valid override status format (2nd nibble) to RF_NOTREADY put error status in STATUS (1st nibble) of status buffer set error status valid to false else put drive status in STATUS (1st nibble) of status buffer Communication with Host via gate array: goes to fail state if HSCK is active (i.e. low) IRQ line is asserted Waits ~2ms (4234 cycles) for HSCK to go active (i.e lo) on timeout, resets outputs to host to inactive and quits comms this loop deasserts irq Sends 10 status nibbles nibbles are inverted HSCK is handshake from host CDCK is handshake frm MCU minimum 77 cycles per nibble HSCK 1 (inactive) -> 0 (active) nibble output CDCK 0 (inactive) ->1 (active) HSCK 0->1 CDCK 1->0 sets status sent flag Gets 10 command nibbles HSCK 1->0 nibble input CDCK 0->1 HSCK 0->1 CDCK 1->0 Entire status/command transfer has timeout of ~3ms (6351 cycles) on timeout, resets outputs to host to inactive and quits comms this loop sets command received flag Checksum of command is checked if bad, resets outputs to host to inactive and quits comms this loop set command valid flag resets outputs to host to inactive Runs command from host Generally comms failures cause it to just run a Nop command checksum failures cause drive error status to be set to STATUS_SUMERROR command is specified by first 2 nibbles of command packet second nibble must be zero or command is invalid first nibble must be < 0xE and != 0x5 or command is invalid command is sent to PC command implementation is run format Absolute if Q subcode CRC is bad OR Q subcode Control ADR mode is not 1 or Q subcode tracknum indicates leadin set status format (2nd nibble) to RF_NOTREADY else store Absolute (RF_A == 0) in status format (2nd nibble) copy ATIME in BCD format from Q subcode buffer to 3rd through 8th nibble (inclusive) store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware format Relative if Q subcode CRC is bad OR Q subcode Control ADR mode is not 1 or Q subcode tracknum indicates leadin set status format (2nd nibble) to RF_NOTREADY else store Relative (RF_R == 1) in status format (2nd nibble) copy relative track TIME in BCD format from Q subcode buffer to 3rd through 8th nibble (inclusive) store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware format Track if Q subcode CRC is bad OR Q subcode Control ADR mode is not 1 or Q subcode tracknum indicates leadin set status format (2nd nibble) to RF_NOTREADY else store Track (RF_T == 2) in status format (2nd nibble) copy track number to 3rd and 4th status buffer nibbles copy Q subcode CONTROL field to 5th status buffer nibble copy Q subcode ADR field to 6th status buffer nibble store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware format TOCO if disc is not validated set status format (2nd nibble) to RF_NOTREADY else set status format (2nd nibble) to RF_TOCO(3) copy leadout start in MM:SS:FF format (BCD) to 3rd through 8th nibble (inclusive) store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware format TOCT if disc is not validated set status format (2nd nibble) to RF_NOTREADY else set status format (2nd nibble) to RF_TOCT(4) copy first track number in BCD format to 3rd and 4th nibbles copy last track number in BCD format to 5th and 6th nibbles copy TOCTVERSION(0) in BCD format to 7th and 8th nibbles store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware format TOCN if disc is not validated set status format (2nd nibble) to RF_NOTREADY store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware else set status format (2nd nibble) to RF_TOCN(5) if requested trac is not valid set status format (2nd nibble) to RF_NOTREADY(F) store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware else copy track start time in MM:SS:FF format (BCD) to 3rd through 8th nibble (includisve) if track is a data track, force MSB of frame to 1 notably, since frame numbers sould be <75 this bit would always be zero otherwise store low nibble of BCD track number in 8th nibble format Error set status format (2nd nibble) to RF_E(6) error number is placed in 3rd nibble note emulator always writes 0 store flags in 9th nibble these seem to correspond to the data, emphasis and mute control bits sent to CD hardware state Stopping: if servo is in STOP status if disc is known present or disc status is unknown set drive status to STOP else set drive status to NODISC state TOCing: if servo is in STOP status if focus is in NOTFOCUSING status set haveDisc to FALSE set haveDiscValid to TRUE set drive status to NODISC else do nothing this tick elif haveDisc is FALSE do nothing this tick (comments suggest this is an abnormal situation) else set drive status to TOCREAD if servo is NOT in PLAY status stop here if haveTOCValid is FALSE process current Q subcode data for TOC entry (see GetTOC) if TOC reading is done set haveTOCValid to true SEEK command is set to mechanism for PBA of program area start stop until next tick else stop until next tick else if havePAValid is TRUE (comments say this isn't supposed to happen) PAUSE command is sent to mechanism else check Q subcode data to see if we have found the start of the Program Area if we have set havePAValid to TRUE SEEK command for start of first track is sent to mechanism PAUSE command is sent to mechanism else if current block Q subcode is invalid or not Mode 1 SEEK to next block else SEEK forward 250 blocks state Reading: state Seeking: state Pausing: state Playing: state Cuing: These 5 states share a common implementation if servo status is STOP do nothing elif servo status is SEEK if mechanism error status is NOERROR set drive status to SEEK else STOP command sent to mechanism emulation state set to STOPPING else if servo status is PAUSE if drive status is NOT DISCEND set drive status to PAUSE else if Q subcode CRC is bad OR Q Control ADR is not mode 1 OR Q subcode tracknum is not lead out set drive status to PLAY else PAUSE command sent to mechanism set drive status to DISCEND state FWDing: if servo status is STOP do nothing elif servo status is SEEK if mechanism error status is NOERROR set drive status to SCAN else STOP command is sent to mechanism emulation state is set to STOPPING elif servo status is PAUSE set drive status to DISCEND else: set drive status to SCAN if Q subcode CRC is valid AND Q Control ADR is mode 1 if Q subcode tracknum indicates leadout PAUSE command is sent to mechanism set drive status to DISCEND else if scanClock is 0 get ATIME from current Q subcode block turn it into an LBA, then PBA Add 100 to it SEEK command sent to mechanism reset scanClock to SCANPLAYTIME(10) state RVSing: if servo status is STOP do nothing elif servo status is SEEK if mechanism error status is NOERROR set drive status to SCAN else STOP command is sent to mechanism emulation state is set to STOPPING elif servo status is PAUSE do nothing else set drive status to SCAN if Q subcode CRC is valid AND Q Control ADR is mode 1 if Q subcode tracknum indcates we're in the leadin area SEEK command is sent to mechanism for beginning of first track PLAY command is sent to mechanism Set emulation state to PLAYING else if scanClock is 0 get ATIME from current Q subcode block turn it into an LBA, then PBA subtract 140 from it SEEK command sent to mechanism reset scanClock to SCANPLAYTIME(10) state Skipping: if servo status is STOP do nothing elif servo status is SEEK if mechanism error status is NOERROR set drive status to TRACKING else STOP command is sent to mechanism emulation state is set to STOPPING elif servo status is PAUSE set drive status to PAUSE else PAUSE command sent to mechanism state DoorClosing: if door state is CLOSING set drive status to TRAYMOVING elif door state is CLOSED set drive status to STOP set request format to absolute set emulation state to CLOSED state DoorClosed: do nothing state DoorOpening: if door state is OPENING set drive status to TRAYMOVING elif door state is OPEN set drive status to DOOROPEN set emulation state to OPEN state DoorOpen: if door status is NOT one of OPEN or OPENING set emulation state to CLOSING command Nop command Stop set request format to absolute if drive status is not DOOROPEN and status is notTRAYMOVING send stop command to mechanism set emulation state to ES_STOPPING command Report Request 4th nibble specifies request type RF_A(0) set absolute time format RF_R(1) set relative time format RF_T(2) request current track info RF_TOCO(3) request disc completion time will be ignored if disc has not been validated yet drive error status will be set to COMMANDERROR request format will be set back to absolute RF_TOCT(4) request start/end tracks on disc if disc is validated and drive is stopped will seek to start of disc and pause there emulation state set to TOCing if disc is validated and drive is not stopped only request format is changed else prepares memory state for TOC read will seek to start of disc and tell mechanism to play emulation state set to TOCing RF_TOCN(5) request start time of track N if drivestatus is DOOROPEN, TRAYMOVING or STOP command will be ignore dand drive error status will be set to COMMANDERROR request format will be set back to absolute requested track number is in the 5th and 6th nibbles in BCD format SEEK command sent to mechanism for start of disc PAUSE command sent to mechansim emulation state set to TOCing RF_E(6) request error info command Read if drive status is DOOROPEN or TRAYMOVING set drive error status to COMMANDERROR and stop processing command check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command location specified in MM:SS:FF format (BCD) in the 3rd through 8th nibbles (inclusive) location is converted to an LBA if location >= leadout start set drive error status to COMMANDERROR and stop processing command program area offset is added to location to convert it to a physical block address PBA is adjusted back 4 SEEK command is sent to mechanism for adjusted PBA PLAY command is sent to mechanism Emulation state set to Reading command Seek Same as Read, except sends Pause instead of Play for second command to mechanism Emulation state set to Seeking command Pause if drive status is DOOROPEN or TRAYMOVING or SCAN set drive error status to COMMANDERROR and stop processing command check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command if drive status is STOP calculates PBA of first track from TOC PBA is NOT adjusted back send SEEK command to mechanism for calculated PBA send PAUSE to mechanism set emulation state to Pausing command Play if drive status is DOOROPEN or TRAYMOVING or DISCEND or DISCIN set drive error status to COMMANDERROR and stop processing command check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command if drive status is TOCREAD or STOP calculates PBA of first track from TOC PBA is adjusted back by 4 SEEK command is sent to mechanism for adjusted PBA send PLAY command to mechanism set emulation state to Playing command Fwd if drive status is NOT one of PLAY, PAUSE or DISCIN set drive error status to COMMANDERROR and stop processing command check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command Send PLAY command to mechanism Emulation state set to Fwding scanClock is set to SCANPLAYTIME(10)?? command Rvs if drive status is NOT one of PLAY, PAUSE or DISCEND set drive error status to COMMANDERROR and stop processing command check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command Send PLAY command to mechanism Emulation state set to Rvsing command TrackSkip if drive status is NOT one of PLAY, PAUSE or DISCEND set drive error status to COMMANDERROR and stop processing command check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command direction to skip is in 4th nibble of command number of tracks to skip is a 16-bit value in the 5th-8th nibbles note tese are physical tracks i.e. loops of the spiral SKIP command is sent to mechanism PAUSE command is sent to mechanism emulation state is set to TSkping command TrackCue if drive status is NOT one of STOP, PLAY, PAUSE, DISCEND, DISCIN or TOCREAD set drive error status to COMMANDERROR and stop processing command if drive status is TOCREAD check request format, if it's TOCT or TOCN, force it to absolute if disc is not validated set drive error status to COMMANDERROR and stop processing command track number is in nibbles 3 and 4 in BCD format calculates PBA of requested track from TOC Sends SEEK command to mechanism for calculated PBA if drive status at start of command was STOP, DISCEND or DISCIN send PLAY command to mechanism emulation state is set to CUING command DoorClose if drive status is NOT one of DOOROPEN or TRAYMOVING set drive error status to COMMANDERROR and stop processing command CLOSE command is set to mechanism emulation state is set to CLOSING command DoorOpen if drive status is DOOROPEN set drive error status to COMMANDERROR and stop processing command if drive servo is not stopped: set request format to absolute OPEN command is sent to mechanism emulation state set to OPENING disc, TOC and program area validitly flags are cleared