Hi,
On 03/23/2015 08:25 PM, Geoff Levand wrote:
Hi,
Just for anyone interested, I bought an FTDI Chip TTL-232RG-VREG1V8-WE (1.8 volt) USB to TTL serial cable and soldered the wire leads the the Hikey J16 as so:
ftdi orange (TX) - Hikey pin2 (RX) ftdi yellow (RX) - Hikey pin4 (TX) ftdi black (GND) - Hikey pin3 (GND) ftdi red (VCC) - open ftdi green (RTS) - open ftdi brown (CTS) - open
Just for the record. I am using a different USB-to-serial thing: FTDI Basic Breakout board [2].
FTDI Basic Breakout board has the jumper which selects between 3.3V and 5.0V IO voltage. For HiKey it must be removed completely - then the TTL outputs of the FTDI chip will be powered from the external power source (HiKey provides 1.8V power source on pin 1).
The connection between HiKey J16 and the FTDI Basic Breakout board 6-pin connector (the silkscreen names are used) is:
VCC <- HiKey pin 1 (1.8V output from HiKey) RXI -> HiKey pin 2 (UART0_RX to HiKey) GND -- HiKey pin 3 (GND) TXD <- HiKey pin 4 (UART0_TX from HiKey)
FT232R datasheet [3] says (VCCIO pin description at page 7) that when the external supply is used, "this supply should originate from the same source as the supply to VCC". Which might mean in my case "don't apply VCCIO before applying VCC to the chip". So I connect the FTDI Basic Breakout board to USB first, then power on the HiKey - just in case.
FTDI has a similar solution: TTL-232RG-VIP-WE cable [1]. But all the 1.8V capable FTDI cables aren't in stock here in Moscow (must be ordered from the UK which means time and money). That's why the [2].
Seems to be working fine.
Same here.
Thanks, Andrey
[1] http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232RG_CAB...
[2] http://www.dfrobot.com/index.php?route=product/product&product_id=147 [3] http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf
-Geoff
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