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product:usb2ax:gpio [2013/04/02 03:19] xevel |
product:usb2ax:gpio [2013/04/02 03:37] xevel |
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//This is advanced stuff!// | //This is advanced stuff!// | ||
- | {{product:usb2ax:USB2AX_bottom_detail.png}} | + | 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 }} | ||
- | 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. | + | 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!** |
- | To get to them, you have to remove the clear piece of heat-shrink tubing that protects the board. Be careful to protect it 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. |
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- | The solder jumper (closed by default) links TX and RX together. This is used to achieve the half-duplex behaviour needed to talk to Dynamixel servos. By cutting the trace between the two solder pads, you can 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. | ||
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* GND - Ground | * GND - Ground | ||
- | 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]]). | + | 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]]). |
See the [[http://www.atmel.com/Images/doc7799.pdf|ATmega32u2 Datasheet]] for more information on these signals! | See the [[http://www.atmel.com/Images/doc7799.pdf|ATmega32u2 Datasheet]] for more information on these signals! | ||