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• Diode Arrays (DA1 & DA2) added

  Jesse Robinson (beacon) • 12/03/2016 at 01:08 • 0 comments

  The NES has 4 diode arrays that appear to provide transient voltage supression (TVS) on the controller ports. They protect the CPU and hex inverters from damage while plugging in controllers.

  Each controller port is connected to two of the arrays. One array dissipates postive voltage spikes to the +5V rail, while the second array dissipates negative voltage spikes from ground.

  I beleive I have found a replacement part that combines both array types into a single package. So we only need one array per controller port now.

  Wurth Elektronic 82401646 TVS Diode Array WE-TVS

  MSOP-8L package

  http://www.mouser.com/ProductDetail/Wurth-Electronics/82401646/

  http://www.mouser.com/ds/2/445/82401646-253741.pdf

  I added the capacitors and pull up resistors on the controller lines as well.

  10 kOhm 0805 Resistors

  http://www.mouser.com/ProductDetail/ROHM-Semiconductor/ESR10EZPJ103/

  5.6 kOhm 0805 Resistors

  http://www.mouser.com/ProductDetail/ROHM-Semiconductor/ESR10EZPJ562/

  330pF 0805 capacitors

  http://www.mouser.com/ProductDetail/Kemet/C0805C331KDRACTU/

  Files NESMOBO.PDF and NESMOBO.SCH updated

• Clocks added

  Jesse Robinson (beacon) • 11/23/2016 at 05:52 • 0 comments

  Schematic Progress:

  -Added the ~21Mhz crystal and supporting components, this connects to the CPU clock (CLK), the PPU clock (U5-CLK) and the cartridge (SYS_CLK) lines. Need to check if the NPN transistor I used in the schematic is a valid substitute for what Nintendo used.

  -Added the reset switch circuit from the Famicom.
  

  -Added the 4Mhz crystal and supporting components, this clock is used by the CIC (10NES) chips. (Both console and cartridge chips)

  I need to go back and change the package size used in CIC clk circuit. 0402 is unnecessarily small, 0805 is more than small enough.

  I'm numbering the passive components as I add them to my schematic, for now disregarding the numbering system obtained from the old schematics (see my research post.)

  As is, the design is a hybrid of the famicom and NES. So really I've building a clone motherboard that requires 4 of the original chips: the PPU, the CPU, and the 2 ram chips. (CIC chip optional) All of the other parts I find equivalents for, with the criteria that mouser.com sells it and the part also exists in an eagle library (or eagle has a similar part of the same package size.) Eventually I'd like to create forks of the schematic, one faithful to the famicom, one faithful to the NES, and various other ones integrating mods. That being said once the hybrid schematic is complete I'll probably start playing with the board layout of my clone first, and shelve the reference schematic forks for later.

  Regarding the CIC lockout chip. I had considered the standard disable method of leaving pin 4 (lock/key) disconnected (or pulled low), which changes the mode and effectively prevents the lockout chip from resetting the CPU due to poor cartridge connections. In this scenario the CIC, which is wired to the physical reset switch, will still reset the CPU when it senses that the reset button is pushed. My approach was to sever the connection from CIC pin 9 (host reset) to the CPU's reset line (/RST). This forces the use of the famicom reset circuit which connects the physical reset switch directly to /RST instead of the CIC. One benefit I see to this approach is that installing the CIC is completely optional at this point, if you don't want to bother transferring it from an old motherboard/cart to this replacement mobo that should be ok - everything will still work, including the reset button. I had considered omitting the CIC completely but I think it could be re-purposed. It was intended to be a DRM mechanism, but it also ended up being a mechanism that wouldn't allow you to play games with possibly bad cartridge connections. I'd like to turn it into a mechanism that merely indicates a connection issue, one that still allows you to play despite the warning.

  Parts added in update:

  -----------------

  cic clock circuit

  C2,C3

  220pf caps

  http://www.mouser.com/ProductDetail/Kemet/C0402C221J5GACTU/

  http://www.mouser.com/ds/2/212/KEM_C1003_C0G_SMD-356956.pdf

  0402 package size

  eagle part: rcl->C-US-> C-USC0402

  XTAL2

  4mhz XTAL

  http://www.mouser.com/ProductDetail/CTS-Electronic-Components/ATS040B/

  HC49U package

  crystal->8M10AHC49T

  R1

  1M ohm resistor

  http://www.mouser.com/ProductDetail/ROHM-Semiconductor/ESR01MZPJ105/

  0402 package size

  rcl- > R_US -> R-US_R0402

  -----------------

  system clock circuit

  XTAL1

  21.47727mhz XTAL

  http://www.mouser.com/ProductDetail/Citizen-FineDevice/HC49US-2147727MABJ-UB/

  HC49US package

  crystal->8M10AHC49T

  R2

  150 Kilo Ohm

  http://www.mouser.com/ProductDetail/ROHM-Semiconductor/ESR10EZPF1503/

  0805 package size

  rcl- > R_US -> R-US_R0805

  R3, R4

  510 Ohm

  http://www.mouser.com/ProductDetail/ROHM-Semiconductor/ESR10EZPJ511/

  0805 package size

  rcl- > R_US -> R-US_R0805

  R5

  220 Kilo Ohm

  http://www.mouser.com/ProductDetail/ROHM-Semiconductor/ESR10EZPF2203/

  0805 package size

  rcl- > R_US -> R-US_R0805

  C4,C5

  51 pF

  http://www.mouser.com/ProductDetail/Murata-Electronics/GRM0335C1E510JA01D/

  0603 package size

  eagle part: rcl->C-US->...

  Read more »

• IC Connections Done

  Jesse Robinson (beacon) • 11/17/2016 at 03:14 • 0 comments

  Completed netting of all pins attached to IC's U1 - U10. Questionable assignments on a few pins though, would like review some more.

  Nintendo's custom 48-pin expansion header has been replaced with a 50 pin ribbon cable connector.
  

  The CIC chip is present but not wired to the CPU's reset line. Currently the CIC host reset line is wired to expansion pin 49.

  The following pins are not connected to anything:
  

  U3: 6,7,10,12

  U10: 5

  P2: 46,50

  Now on to the circuits with passive components......

  TO DO:

  Circuits:

  Reset Switch

  Power switch

  System Clock

  CIC Clock

  CPU Analog Audio IN/OUT

  PPU Analog Video OUT

  Joypad pullup resistor banks

  Joypad diode banks

  Joypad connectors

  misc pull resistors,caps

  AV line level output circuits

  usb power in

  Other:

  famicom io ports

  fork schematic,replace ram with sourceable chips, update pinout

  look for cheaper/smaller/modern components

  ....this could take awhile

• Starts with research

  Jesse Robinson (beacon) • 11/17/2016 at 03:00 • 0 comments

  References:

  Schematics:

  NES: http://gamesx.com/wiki/doku.php?id=schematics:console_related_schematics

  FAMICOM:

  
  

  Pinouts:

  CPU: https://wiki.nesdev.com/w/index.php/CPU_pin_out_and_signal_description

  CIC: https://wiki.nesdev.com/w/index.php/CIC_lockout_chip_pinout

  NES EXP port: https://wiki.nesdev.com/w/index.php/NES_expansion_port_pinout

  60&72pin cart connectors: https://wiki.nesdev.com/w/index.php/Cartridge_connector

  Libraries:

  https://www.element14.com/community/docs/DOC-64303/l/fairchild-cad-libraries-for-cadsoft-eagle-software

  https://www.element14.com/community/docs/DOC-64304/l/texas-instruments-cad-libraries-for-cadsoft-eagle-software

  http://www.pcserviceselectronics.co.uk/eagle/con-3m-skt-header.lbr

  https://github.com/jpwright/eagle-lbr/blob/master/nintendo.lbr

  *renamed nintendo-cart.lbr

  https://github.com/Sputnick85/eagle_nintendo/blob/master/nintendo.lbr

  *renamed nintendo-av.lbr

  https://github.com/spacerace/Eagle-Libraries/blob/master/commodore/Mos6502.lbr

  *duplicated, edited each, and renamed as:

  Ricoh2C02.lbr

  Ricoh2A03.lbr

  Eagle Help:

  https://intranet.ee.ic.ac.uk/t.clarke/EAGLE/The EAGLE Guide.pdf

  https://learn.sparkfun.com/tutorials/using-eagle-schematic

  https://hackaday.com/2008/10/20/parts-chip-sockets-for-dual-in-line-package-dip/

  Rough BOM:

  Resistors

  RM1 10K 11x 12x?

  R1 100

  R2 100

  R3 10K

  R4 20K

  R5 12K

  R6 2.2K

  R7 100K

  R8 10K

  R9 1.2K

  R10 1.2K

  R11 220K

  R12 220

  R13 150K

  R14 1.2K

  Diodes:

  D1 1S953

  Caps:

  IC1 30p

  C1 0.47u

  C2 1u

  C3 51p

  C4 51p

  C5 5p

  C6 15p

  C7 0.1u

  C8 0.1u

  C9 220p

  C20 68p

  C21 330p

  C22 18p

  C23 30p

  Crystals:

  XTAL1 (CPU/PPU CLK): 21.477272 MHz

  XTAL2 (CIC CLK):4 Mhz

  Transistors:

  Q1 2SA937

  Chips:

  U1 SRAM (for CPU, PPU) 2048x8

  DIP 24 - ic-package->DIL24->DIL24-6 0.6inch

  http://pdf1.alldatasheet.com/datasheet-pdf/view/154361/SONY/CXK5816PN/M-15L.html

  U2 74LS373 - PPU Memory Bus latch

  TI SN74LS373DWR

  http://www.mouser.com/ProductDetail/Texas-Instruments/SN74LS373DW/?qs=sGAEpiMZZMu2QtOrmdJ1/TEA7XqGnVH%2bjIYdeprvKFA=

  http://www.ti.com/lit/ds/symlink/sn74ls373.pdf

  U3 LS139 - demulitplexer

  DM74LS139M Fairchild Semiconductor

  http://pdf.datasheetcatalog.com/datasheets/90/232315_DS.pdf

  http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/DM74LS139M/?qs=0kuPHEOuoRTXyP%2bV8FErEw== - 74xx-us -> 74*139->74LS139N

  U4 SRAM (for PPU) 2048x8

  Same as U1: DIP 24 - ic-package->DIL24->DIL24-6 0.6inch

  U5 PPU RP2C02

  http://nesdev.com/2C02 technical reference.TXT

  U6 CPU RP2A03

  https://wiki.nesdev.com/w/index.php/CPU_pin_out_and_signal_description

  U7 40H368

  Inverting 3 state logic line driver

  http://www.mouser.com/Search/Refine.aspx?Keyword=CD74HC368

  http://www.ti.com/lit/ds/symlink/cd74hc367.pdf

  U8 40H368

  Same as U7

  U9 74HCV04

  hex inverter, 14-pin

  Texas Instruments SN74HC04N

  https://www.digikey.com/product-detail/en/texas-instruments/SN74HC04N/296-1566-5-ND/277212

  http://www.ti.com/lit/ds/symlink/sn74hc04.pdf

  U10 3193A (CIC)

  https://wiki.nesdev.com/w/index.php/CIC_lockout_chip_pinout

  16 pin dip

  P2 Expansion Port Substitute:

  8550-4500 3M Reverse IDC connector 50 pin

  https://www.digikey.com/catalog/en/partgroup/5100-series/27171

  http://multimedia.3m.com/mws/media/22253O/3mtm-100-in-plr-bmskt-100x-100cntrbmp-ra-sldrtails-ts0414.pdf //5100 series vertical connector

  http://www.pcserviceselectronics.co.uk/eagle/3msocket.php

  Planned Port numbering:

  P1 72 pin nes cartridge connector

  P2 nes expansion port

  P3/4 player1/2 controller ports

  P5 power&reset switches/mic in?

  P6 av out

  P7 usb power port

  P8 60 pin famicom cartridge connector

  P9 famicom expansion port

  P10 mic in?

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