Prototype 2（用ft2232c做的jtag）

liyf 发表于 2015-2-10 15:24:12

Prototype 1的改进版，用ft2232c做的jtag

My second prototype is a PCB with about 7 x 6 cm size with the followingcomponents on board:

[*]FT2232C with 93C56 EEPROM

[*]Step up/down regulator to guarantee 5.0 Volt from 4.5 to 5.5 USB Voltage.

[*]RS-232 Level Shifter (MAX3241)

[*]ADuM1401BRW I-Coupler for JTAG port level shifting and electrical isolation.

[*]RS-232 connector D-SUB9

[*]JTAG Connector

Be aware, the design has some flaws:

[*]The I-Coupler does not work at highest speed (ca. 6 MHz). It can only beused with 3 MHz and slower. The reason is, that the couplers have a ratherlarge propagation delay of about 50 nsec.

[*]The I-Coupler can only be used for 3.3V and 5V targets. Future targetvoltages, especially 2.5 and 1.8V are not supported.

[*]The reset signals SRST and TRST are not 3-state signals. Depending on theschematics of the target this can cause problems.

制作资料

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