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SPI Isolator ------------ This is a PCB for allowing arbitrary motherboards to have their SPI flash chip isolated from the motherboard when powered off (or via control signal), to allow external (ISP) programming. KiCad sources are in the repo, but for simple purchasing, there's the PCB shared in oshpark: https://oshpark.com/shared_projects/ZljIshjt And the parts list: - Example URLs R1, R2: 4k7 0805 resistor - http://uk.farnell.com/walsin/wr08x4701ftl/res-thick-film-4k7-1-150v-0805/dp/2502731 C1: 1u 0805 capacitor - http://uk.farnell.com/kemet/c0805c105z3vactu/ceramic-capacitor-1uf-25v-y5v/dp/1269997 D1: schottky SOD-323 diode - http://uk.farnell.com/nxp/pmeg2005aea/diode-schottky-sod-323/dp/8737843 U1: 74LVC4066 - http://uk.farnell.com/on-semiconductor/mc74lvxt4066dr2g/analogue-switch-quad-spst-nsoic/dp/2464564 , http://eu.mouser.com/ProductDetail/NXP-Semiconductors/74LVC4066D118 P2: 2x4 IDC header - http://uk.farnell.com/te-connectivity-amp/826942-4/header-straight-2x4way/dp/1248160 U2: SO-8 SPI flash chip - http://uk.farnell.com/spansion/s25fl164k0xmfi011/ic-memory-flash-64mbit-soic-8/dp/2363323 Oh, and if you like this, pizza money donations are accepted via paypal: urjaman at gmail dot com. Known unsupported: Quad I/O. If you have a motherboard that needs that, message me, for a small donation I could make a version that supports Quad I/O ;) Build Howto and Usage (beta, untested) -------------------------------------- solder the components on the PCB, a probably fine order is starting from the underside first... remove the flash chip from the target machine, and attach the PCB as near as possible to its layout (maybe with double-sided tape), but not over the layout. Connect small (patch, "green wire") wires from the 6 places on the edge of the PCB to the layout the 2x4 ISP connector is compatible with the one in the PC Engines APU series, so if you have an ISP lead for them, it should work for this, otherwise, the pinout is: 3V3 1 2 GND !CS 3 4 SCK SO 5 6 SI -- 7 8 buffer en/!dis NOTE: The 160129 version was not compatible with the APU pinout (which is a dediprog programming pinout), the MOSI and MISO were accidentally swapped. The analog switch/buffer is normally controlled by the 3V3 power on the motherboard, so the chip is externally programmable when the motherboard 3.3V supply is OFF The buffer control line is an extension to the APU connector (it had nothing there), that can be used to program externally even if the target motherboard is running. To do that, connect pin 8 of the ISP header to ground, but preferably not too hard; if you connect the header the wrong way around and there is some other ground connection between the programmer and the motherboard (eg. RS232), this would connect the 3V3 line to ground. So a suggested safer circuit is: pin 8 - 50 ohm - switch - pin 2 With parts for this extension: http://uk.farnell.com/multicomp/mcknp03uj0500b00/resistor-wirewound-50r-5-3w/dp/1903828 http://uk.farnell.com/multicomp/mcr13-5-05/switch-toggle-spst-off-on-so/dp/2128120