Quick Start - grandideastudio/jtagulator GitHub Wiki
The JTAGulator is powered from the host computer’s USB port and uses an industry-standard FTDI FT232RL device to provide the USB connectivity. The device will appear as a Virtual COM port and will have a COM port or device tty automatically assigned to it.
All communication is 115200 bps, 8 data bits, no parity, 1 stop bit. Use a terminal program (for example, PuTTY, CoolTerm, minicom/picocom, or screen) to communicate with the JTAGulator.
Upon successful connection to a host, the JTAGulator's LED will turn YELLOW and it will wait until the user presses any key from within the terminal program. The JTAGulator will then send its welcome header.
If the JTAGulator's LED turns RED on power-up, then it is in a secondary operating mode (for example, logic analyzer or OpenOCD) and is waiting for commands from the respective external software tool. To exit and return to normal JTAGulator functionality, open your terminal program and press Ctrl-X.
When the JTAGulator is ready to receive commands, it will send a > to the host and the LED will turn GREEN. It will then wait in an idle state until it receives a valid command, at which time it performs the command and returns any command-specific response. If an invalid command is received, the JTAGulator will respond with a ?.
Set the target I/O voltage (VADJ) using the V command. This will ensure that the target receives signals within its acceptable logic levels. The voltage can be determined by locating and measuring VCC on the target board or by checking the data sheet of the specific component to which you will be connecting (if known).
Attach the target’s points to the JTAGulator using the screw-in terminal blocks or via the 2x5 male headers, starting at CH0 and incrementing sequentially as needed. Ensure there is a shared GND connection between the JTAGulator and target board. VADJ should not be connected to the target board (it is made available on the headers for testing and future use). The 2x5 headers are compatible with Bus Pirate probes and 0.1" jumper wires.
The JTAGulator's input protection circuitry allows for a maximum input voltage of VADJ + 10 V on each channel. Exceeding this value may cause damage to on-board components. The input protection circuitry may, at times, conflict with the target and improperly affect signal levels and detection results. Hardware modifications are available that will improve target compatibility at the expense of input protection and/or level translation functionality.
