User Tools
product:usb2ax:gpio
Differences
This shows you the differences between two versions of the page.
| Next revision | Previous revision Last revision Both sides next revision | ||
|
product:usb2ax:gpio [2013/04/02 02:16] xevel created |
product:usb2ax:gpio [2013/04/02 03:37] xevel |
||
|---|---|---|---|
| Line 3: | Line 3: | ||
| //This is advanced stuff!// | //This is advanced stuff!// | ||
| - | On the bottom of the PCB of the USB2AX are exposed 8 0.1" pads. They provide access to 6 very useful pins of the ATmega and to ground. | + | On the bottom of the PCB of the USB2AX are exposed eight 0.1" pads. They provide access to some useful pins of the ATmega and to ground. |
| + | {{ product:usb2ax:USB2AX_bottom_detail.png?300 }} | ||
| + | |||
| + | To get to them, you have to remove the clear piece of heat-shrink tubing that protects the board. **Be careful to protect the board again before using it!** | ||
| + | |||
| + | The solder jumper (closed by default) links TX and RX together to form the DATA line. This is used to achieve the half-duplex behavior needed to talk to Dynamixel servos. By cutting the trace between the two solder pads, you can untie them and use the USB2AX as a normal USB to full-duplex TTL serial. Then, if you want to get back to the original behavior, just solder back the two pads together. | ||
| Notice that ground is common between the USB plug, the MCU and the Dynamixel connector. | Notice that ground is common between the USB plug, the MCU and the Dynamixel connector. | ||
| + | ---- | ||
| The three pads on the side of the board are useful to reset the board and to run the stock USB bootloader. This is very useful when developing a custom firmware: if you break the auto-update feature (or simply don't have one), you can always [[product:usb2ax:firmware_update|run the bootloader]] and upload another firmware.\\ | The three pads on the side of the board are useful to reset the board and to run the stock USB bootloader. This is very useful when developing a custom firmware: if you break the auto-update feature (or simply don't have one), you can always [[product:usb2ax:firmware_update|run the bootloader]] and upload another firmware.\\ | ||
| - | It is recommended not to use these as GPIO unless you really know what you are doing. | + | It is recommended not to try to use these as GPIO unless you really know what you are doing. |
| * GND - Ground | * GND - Ground | ||
| * HWB - PD7, Hardware Boot (active low) | * HWB - PD7, Hardware Boot (active low) | ||
| Line 21: | Line 27: | ||
| * GND - Ground | * GND - Ground | ||
| + | The ICSP programming interface uses the SPI pins but might also need access to VCC. In this case, carefully get VBUS on the USB connector (see [[product:usb2ax:specs#Schematics|schematics]]). | ||
| - | The ICSP programming interface uses the SPI pins but might also need access to VCC. In this case, carefully get VCC on the USB connector (see [[product:usb2ax:specs#Schematics|schematics]]). | + | See the [[http://www.atmel.com/Images/doc7799.pdf|ATmega32u2 Datasheet]] for more information on these signals! |
| - | + | ||
product/usb2ax/gpio.txt · Last modified: 2013/04/02 03:41 by xevel
Page Tools
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Share Alike 4.0 International
