Pololu Wixel - Manual (Page 33)

Default Pinout
Pin Function
P1_0 DTR general-purpose output pin
P1_1 RTS general-purpose output pin
P1_2 DSR general-purpose input pin
P1_3 CD general-purpose input pin
P1_5 PA_PD radio transmit debug output
P1_6 TX transmits serial data (0–3.3 V)
P1_7 RX receives serial data (0–3.3 V, not 5 V tolerant)
P0_0 Arduino DTR for wireless Arduino programming when used with the Wixel shield
Description
This device appears to the USB host as a Virtual COM Port (with USB product ID 0x2200). If you are using Windows,
you should see an entry labeled “Wixel” in your Device Manager in the “Ports (COM & LPT)” category while the
app is running.
There are three basic serial modes that can be selected:
1. USB-to-Radio: Serial bytes from the USB virtual COM port get sent to the radio and vice versa.
2. UART-to-Radio: Serial bytes from the UART’s RX line get sent to the radio and bytes from the radio get
sent to the UART’s TX line.
3. USB-to-UART: Just like a normal USB-to-TTL serial adapter, bytes from the virtual COM port get sent on
the UART’s TX line and bytes from the UART’s RX line get sent to the virtual COM port.
You can select which serial mode you want to use by setting the serial_mode parameter to the appropriate number
(from the list above) or you can leave the serial mode at 0 (which is the default). If the serial_mode is 0, then the
Wixel will automatically choose a serial mode based on how it is being powered as described in the table below, and
it will switch between the different serial modes on the fly.
Auto-Detect Serial Mode
(serial_mode = 0)
Power Source Serial Mode
USB only USB-to-Radio
VIN only UART-to-Radio
USB and VIN USB-to-UART
The RX pin has an internal 20 kΩ pull-up resistor.
The PA_PD pin (P1_5) is a debugging output that goes low while the Wixel is transmitting a packet on the radio.
The serial data format used by this app is 8 data bits, one stop bit, with no parity, which is often expressed 8-N-1. The
data is non-inverted, so 0 V represents 0 and 3.3 V represents 1.
Pololu Wixel User's Guide © 2001–2014 Pololu Corporation
9. Wixel Apps Page 33 of 64