Annoying process of hooking Pi to display and keyboard forced me to look for a serial connection option. This way I will just have to switch between two terminal windows, instead of messing with the cables.
I've got a dongle named "USB 2.0 to TTL Uart 5-Pin CP2102 Module Serial Converter", based on reviews it should work in this configuration.
Description says TTL, which usually means 5V signal levels, but in fact Rx/Tx lines shows 3.3V.
Computer recognized the device as:
$system_profiler SPUSBDataTypeFor this device to be detected as serial port on the PC side drivers needed. After installing the drivers, two new devices appear (on OSX):
...
CP2102 USB to UART Bridge Controller:
Product ID: 0xea60
Vendor ID: 0x10c4 (Silicon Laboratories, Inc.)
Version: 1.00
Serial Number: 1
Speed: Up to 12 Mb/sec
Manufacturer: Silicon Labs
Location ID: 0xfa130000 / 6
Current Available (mA): 500
Current Required (mA): 100
...
$ ls /dev/*SLAB*Hooking up the Pi:
/dev/cu.SLAB_USBtoUART /dev/tty.SLAB_USBtoUART
Only G(ground),R(rcv),T(trx) pins are needed.
Ground connects to ground, R connects to TXD, T connects to RXD.
To open serial terminal on OSX:
$screen /dev/tty.SLAB_USBtoUART 115200 8N1Where 11520 is a bit-rate expected by Pi, and 8N1 - 8 bits, No parity, one stop bit.
And here how the space (0x20) looks on the wire
Yellow channel is PC transmit, and blue - receive. Since I'm in terminal, my input is echoed back. The bits are sent from low to high order, so 0010000 (0x20) actually becomes 00000100.
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