Thank you! I swapped out my phone charger for my iPad's wall wart to power the raspberry pi, and I did some power-saving stuff like installing raspbian lite, disabling LEDs and radios, and accessing the pi via SSH rather than a monitor and HDMI. And it worked! The drive seems to be functioning perfectly fine even after doing some reads/writes on the chip.

On Tue, Mar 6, 2018 at 3:42 PM, Nico Huber <nico.h@gmx.de> wrote:

Hi,

On 06.03.2018 00:20, Jesse Li wrote:
> Hey,
>
> I'm trying to read from and flash to a W25X40ALSNIG [0] that's still
> mounted to its hard drive PCB. Following the table from the raspberry pi
> wiki page [1], and assuming the raspberry pi pin numbers it mentions are
> physical pin numbers (and not the pi's strange GPIO numbering scheme) I
> connected the legs of the flash chip to the raspberry pi's GPIO pins.
> However, when the two are attached, the pi won't boot (it'll show the three
> raspberries in the corner, then it shuts off). I've isolated this to the
> VCC (connected to header 17, 3v3) and GND (connected to header 25, GND) ,
> where having all of the legs of the flash chip detached from the pi except
> for those two will reproduce my problem (I hope testing that didn't
> actually kill the chip). What am I missing?

the circuitry of your hard drive is most likely not prepared for powe-
ring the flash chip directly at its VCC pin. You probably power all 3V3
parts on that PCB which is too much for your RPi's PSU / voltage conver-
ter.

Killing the SPI flash is unlikely. I can't say the same about other
chips on the board, though. Reading the flash while the hard drive is
up and running, probably also isn't a good idea. You could desolder the
flash chip, or try a stronger PSU, both ways have chances to break some-
thing.

Nico