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We've just made our custom board with an atmega1280 and a FT232RL to communicate with a raspberry pi 2. The board works well, bootloader:ok, arduino sketch upload:ok, serial comm to 1Mb:ok.

As I've already tested this before with an usb hub : the raspberry, only connected through an usb port, can start and boot. No problem.

And we imagine a board with the same feature, but nope...

With the default config of the FT232RL, when I connect the board via usb with a pretty 5V, the raspberry don't boot. If I connect the +5V of the board to the raspi GPIO with a wire, the raspi starts. And if I remove this wire, the raspberry stay on... So the usb power do the job!

I'm thinking to a probably problem with the ftdi eeprom's config ? Here is the last config I used for ftdi_eeprom.conf :

# Identify the device to write.
vendor_id=0x0403    # Vendor ID
product_id=0x6001   # Product ID
max_power=0         # Max. power consumption: value * 2 mA. Use 0 if self_powered = true.

# Strings
manufacturer="FTDI"         # Manufacturer
product="EB_BOARD"          # Product
serial="EB_BOARD_V2_0"      # Serial Number

# Options
self_powered=true          # Turn this off for bus powered
remote_wakeup=true          # Turn this on for remote wakeup feature
use_serial=true            # Use the serial number string

# Normally out don't have to change one of these flags
#BM_type_chip=true           # Newer chips are all BM type
in_is_isochronous=false     # In Endpoint is Isochronous
out_is_isochronous=false    # Out Endpoint is Isochronous
suspend_pull_downs=false    # Enable suspend pull downs for lower power
change_usb_version=false    # Change USB Version
usb_version=0x0200          # Only used when change_usb_version is enabled

# Dump to file
filename=ftdi_eeprom.dump

Please help us ! We make a beautiful board design, but now we have a wire traversing the two boards... So sad :)

Thank you!

Edit : the usb port provide 5v/3A to the raspberry.

G33k Labs
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  • I dont think the ftdi part itself if it regulates power can deliver nearly enough to power the raspberry pi (I cant even get one to power an esp8266). if the regulator is not part of the ftdi then you need to just see what the power requirements are for the raspberry pi (just measure it when it is running directly from usb for example, if you have the ability to design a board you have the ability to do this measurement as well as of course design the board to deliver the power to the raspi). – old_timer Jan 26 '16 at 02:05
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    you may want to read http://raspberrypi.stackexchange.com/questions/28310/whats-the-problem-with-backfeeding – ilia Feb 15 '16 at 15:49
  • Exactly, rpi can not boot without being powered from usb connecter or gpio. We decide to "hack it" by soldering wires from usb power connector to gpio. Disgusting but it works ! – G33k Labs Feb 19 '16 at 11:54

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