Debug Board v2
The debug board provides these key components.
The Schematics of this board can be found at http://people.openmoko.org/laforge/doc/hardware/neo1973_debug_board/neo1973_debugboard_v2_schematics.pdf
This bus-powered hub
- attaches to the laptop using its upstream port
- attaches to the FT2232D for JTAG and serial console on downstream port 1
- attaches to USB-A connectors using downstream ports 2 and 3
For the USB hub we use the TUSB2046B chip.
Using the hub, you can have access to the phone, JTAG and serial simultaneously, through a single USB cable. You can actually even charge the phone (100mA slow charge) using that downstream port.
If you have 2 free USB ports on your PC, it is better to plug the debug board and the Neo1973 into the PC independently (rather than using the hub). This will allow the Neo1973 to charge at the full 500mA rate, and will also allow the debug-board USB to be unplugged/reconnected without affecting the Neo1973.
JTAG using FT2232
Basically, we integrate a USB-JTAG adaptor similar to the [Amontec JTAGkey-tiny]. The actual reference design that we used (Thanks to Joern!) can be found at http://www.oocdlink.com
This provides us full JTAG debugging, at about 150times the speed of the wiggler
The actual JTAG port is connected with
- the phone (via debug flex cable)
- A separate 20-pin header using standard ARM-JTAG pinout
- this allows the user to use this device as JTAG adaptor even for other arm-based devices
Instead of replicating a true RS232 port, we wanted to use a USB serial converter chip, such as the FT232 or the PL2303.
As it turns out, we can even use the second port of the FT2232 simultaneously with the JTAG. So no extra FT232 or PL2303 is required.
Tri-State Serial Port
The serial port needs a tri-state driver, since it is both connected to the GSM modem AND to the debug board. We drive the tri-state driver by an inverted GSM_EN signal (pin 7 on FPC connector).
Please see Neo1973 Debug Board v2/EEPROM if you have an "early adopter" board with USB ID 0403:0610. If your board shows up as USB ID 1457:5118 then you can ignore this step.
Please make sure you have libftdi-0.8 or later. Earlier versions are known to cause problems
Furthermore, you will need to do the following:
ftdi_sio module option
rmmod ftdi_sio modprobe ftdi_sio vendor=0x1457 product=0x5118
or the equivalent in your modules.conf
Please install the rules from http://people.openmoko.org/laforge/misc/debug_board_v2/udev_rules/
Please use the driver from http://people.openmoko.org/laforge/misc/debug_board_v2/windows_drivers/
- Connecting Neo1973 with Debug Board v2
- Connect your favorite embedded project to the Debug Board v2:
- J1 - is a regular 20 pin ARM JTAG at 3.3V level with 5V tolerance
- J10 - is a 3.3V serial connected to portB of the FTDI2232D
pin name 1 TXD 2 RXD 3 RTS 4 CTS 5 DSR 6 DTR 7 DCD 8 RI 9 GND 10 VCC (3.3V)
Actually using it
The Linux kernel of your host system will create virtual serial devices called /dev/ttyUSBx where 'x' is a sequentially assigned number. If you don't have any other USB serial converters attached to your machine, the device name will be /dev/ttyUSB1 for the serial port. A /dev/ttyUSB0 will also be created initially, but will disappear once openocd connects to the JTAG port.
You can use your favourite terminal emualtor (screen, minicom, cu, zc, ...) just like for any other/real serial port. The baud rate should be set to 115200. You may use gdb as well (eg. target remote /dev/ttya).
Please see OpenOCD#OpenOCD_and_Debug_Board for some more information.
We previously had Neo1973 Debug Board v1 (inherited from some weird engineers who must have seen Brazil too often). Version 1 was never shipped to phase-0 or phase-1, and not sold to anyone.
Changes from v1 to v2
- get rid of ethernet
- we don't need it, and
- we especially don't want a 40pin parallel 66MHz bus going between two pcb's
- get rid of 7-segment LED displays
- not really needed. We have a serial port
- could be replaced by one or two GPIO LEDs
- get rid of built-in wiggler
- nobody has a parallel port on the laptop these days
- get rid of li-ion battery (including charger)
- the device can be fully usb powered by the laptop
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