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B68k av
Lougous/b68k-avAudio and video board for b68k computer
- Size
- 100 × 100 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 86
- Nets
- 157
- Pads
- 523
- Tracks, vias
- 2,259, 222
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 4 Jun 2024
- Updated
- 10 Sep 2024
Overview
B68k av is an open-source printed circuit board by Lougous, from the Lougous/b68k-av repository on GitHub, published under the MIT licence. It is a 2-layer board of 100 × 100 mm with 86 parts on 157 nets, routed with 2,259 tracks and 222 vias.
It is built around the 74LS373SC and 74LS245SC. Its parts include 33 capacitors, 20 resistors, 9 ICs, 7 connectors and 5 diodes. It belongs with the fPGA and programmable logic and audio and music boards and the FPGA and CPLD boards of this library.
Main components
2
74LS373SC
--55℃~+125℃ 1 2.6mA 24mA 38ns@5V,150pF 4.75V~5.25V 74LS 8 Output enable Tri-State - Buffers, Drivers, Receivers, Transceivers ROHSTexas InstrumentsBuffers, Drivers, Receivers, Transceivers74LS245SC
-0℃~+70℃ 12ns@5V,45pF 15mA 24mA 4.75V~5.25V 74LS 8 Bidirectional Output enable Schmitt trigger Tri-State - Buffers, Drivers, Receivers, Transceivers ROHSTexas InstrumentsBuffers, Drivers, Receivers, Transceivers
README
README.mdOverview
This board provides audio and video capabilities to the b68k computer. Main components:
- CPLD for local bus decoding and FPGA configuration
- flex FPGA
- SRAM 16-bits, 256kiB or 512 kiB
- video RAMDAC
- OPL2 audio chip
external interfaces: video (VGA, DIN 15 pins) and audio (3.5mm jack)
Memory mapping
The AVMGR CPLD decodes local bus accesses to address itself, the RAMDAC, the OPL2 or the flex FPGA.
| address range | size | memory area |
|---|---|---|
| 00000h - 0007Fh | 128B | AVMGR registers. address bit 0 is ignored |
| 00080h - 000FFh | 128B | flex registers |
| 00100h - 0017Fh | 128B | RAMDAC registers. address bit 0 is ignored |
| 00180h - 001FFh | 128B | OPL2 registers. address bit 0 is ignored |
| 00200h - 07FFFh | 512B*63 | mirrors x63 address range 000h-1FFh |
| 08000h - 0FFFFh | 32kiB | SRAM access (upper 32kiB, banking through flex register) |
| 10000h - 1FFFFh | 64kiB | SRAM access (banking through flex register) |
AVMGR registers
These registers provide an interface to configure the flex FPGA. Address bit 0 is ignored, so that odd address target the same register as at even address.
| address offset | name | description |
|---|---|---|
| 00000h | cfgnsts | bit 0: (r) flex nSTATUS signal bit 1: (r) flex CONF_DONE signal bit 6: (rw) flex nCONFIG signal bit 7: (rw) flex reset signal (active low) |
| 00002h | dat | bit 0: (rw) flex DAT0 signal When this register is written, the flex DAT0 signal is driven and a pulse is generated on DCLK |
| 00004h | dbg0 | spare register for debug purpose |
| 00006h | dbg1 | spare register for debug purpose |
These registers mirror every 8 bytes.
OPL2 registers
Provide access to the 2 OPL2 registers. Address bit 0 is ignored, so that odd address target the same register as at even address.
| address offset | name | description |
|---|---|---|
| 00000h | regad | OPL2 Address (write) and status (read) register |
| 00002h | regdt | OPL2 Data register |
RAMDAC registers
Provide access to the RAMDAC registers (Bt476 / IMS G176 or compatible). Address bit 0 is ignored, so that odd address target the same register as at even address.
| address offset | name | description |
|---|---|---|
| 00000h | ad_write | Address Register (RAM Write Mode) |
| 00002h | color | Color Palette RAM |
| 00004h | mask | Pixel read Mask Register |
| 00006h | ad_read | Address Register (RAM Read Mode) |
flex registers
See flex FPGA documentation.
BOM
| Reference | Part |
|---|---|
| RN1 | not populated |
| U1 | 74F245 |
| U2 | EPM7064SLC44-10 |
| U3 | MPC6002 |
| U4 | LM337 |
| U6 | EPF10K10LC84-4 |
| U7, U8 | 74F373 |
| U11 | YM3812 (OPL2) |
| U12 | KDA0476BCN-66 |
| D5 | BAT48 (shottky) |
| X1 or X3 | 25-MHz |
Parts
86| Qty | Value | Footprint | References |
|---|---|---|---|
| 12 | 100nF | Capacitor_THT:C_Disc_D4.3mm_W1.9mm_P5.00mm | C1, C2, C3, C4, C5, C6, C14, C15, C19, C20, C21, C24 |
| 6 | 200nF | Capacitor_THT:C_Disc_D4.3mm_W1.9mm_P5.00mm | C8, C9, C10, C11, C12, C13 |
| 6 | 6n8 | Capacitor_THT:C_Disc_D4.3mm_W1.9mm_P5.00mm | C7, C16, C17, C25, C26, C27 |
| 6 | MountingHole | MountingHole:MountingHole_2.7mm_M2.5_DIN965_Pad | H1, H3, H4, H5, H6, H7 |
| 5 | 1k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R2, R3, R4, R6, R7 |
| 5 | D | Diode_THT:D_DO-34_SOD68_P7.62mm_Horizontal | D1, D2, D3, D4, D5 |
| 4 | 4k7 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R17, R18, R19, R20 |
| 3 | 75 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R8, R9, R10 |
| 2 | 100n | Capacitor_THT:C_Disc_D4.3mm_W1.9mm_P5.00mm | C18, C30 |
| 2 | 100u | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C37, C38 |
| 2 | 1k17 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R13, R16 |
| 2 | 1uF | Capacitor_THT:CP_Radial_Tantal_D4.5mm_P5.00mm | C22, C39 |
| 2 | 220 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R11, R12 |
| 2 | 300k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R14, R15 |
| 2 | 4u7 | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C28, C29 |
| 2 | 74LS373 | Package_DIP:DIP-20_W7.62mm_Socket | U7, U8 |
| 2 | Conn_02x20_Odd_Even | Connector_PinSocket_2.00mm:PinSocket_2x20_P2.00mm_Vertical_SMD | J4, J6 |
| 2 | L | Inductor_THT:L_Axial_L5.3mm_D2.2mm_P2.54mm_Vertical_Vishay_IM-1 | L1, L2 |
| 1 | 10uF | Capacitor_THT:CP_Radial_Tantal_D4.5mm_P5.00mm | C23 |
| 1 | 147 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical | R5 |
| 1 | 20 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R1 |
| 1 | 74LS245 | Package_DIP:DIP-20_W7.62mm_Socket | U1 |
| 1 | ADV476_DIP28 | Package_DIP:DIP-28_W15.24mm_Socket | U12 |
| 1 | CXO_DIP14 | Oscillator:Oscillator_DIP-14 | X3 |
| 1 | CXO_DIP8 | Oscillator:Oscillator_DIP-8 | X1 |
| 1 | Conn_01x03 | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J3 |
| 1 | Conn_01x05 | jack:ASJ-5-X_3.5mm_Jack | J8 |
| 1 | Conn_02x05_Odd_Even | Connector_PinHeader_2.54mm:PinHeader_2x05_P2.54mm_Vertical | J5 |
| 1 | Conn_02x10_Odd_Even | Connector_PinHeader_2.54mm:PinHeader_2x10_P2.54mm_Vertical | J1 |
| 1 | DB15_Female_HighDensity_MountingHoles | Connector_Dsub:DSUB-15-HD_Female_Horizontal_P2.29x1.98mm_EdgePinOffset3.03mm_Housed_MountingHolesOffset4.94mm | J2 |
| 1 | EPF10K10LC84 | Package_LCC:PLCC-84_THT-Socket | U6 |
| 1 | EPM7064SL44 | Package_LCC:PLCC-44_THT-Socket | U2 |
| 1 | LM337L_TO92 | TO_SOT_Packages_THT:TO-92_Inline_Narrow_Oval | U4 |
| 1 | MCP6002-xP | Package_DIP:DIP-8_W7.62mm_Socket | U3 |
| 1 | SolderJumper_2_Bridged | Jumper:SolderJumper-2_P1.3mm_Bridged_RoundedPad1.0x1.5mm | JP2 |
| 1 | YM3812 | Package_DIP:DIP-24_W15.24mm_Socket | U11 |
| 1 | locked | MountingHole:MountingHole_2.7mm_M2.5_DIN965_Pad | H2 |
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Questions
How big is the B68k av PCB?
It measures 100 × 100 mm and has 2 copper layers, 1.6 mm thick.
What parts does the B68k av use?
86 parts, built around the 74LS373SC and 74LS245SC. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the B68k av KiCad files?
From the Lougous/b68k-av repository on GitHub, at the commit this page was made from: the board is board/av.kicad_pcb and its schematic board/audio_out_pwm_stereo.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the B68k av design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).