Z-World RabbitCore RCM3200 User Manual - page 32

28

RabbitCore RCM3200

A.2  Bus Loading

You must pay careful attention to bus loading when designing an interface to the 

RCM3200. This section provides bus loading information for external devices.

Table A-2 lists the capacitance for the various RCM3200 I/O ports.

Table A-3 lists the external capacitive bus loading for the various RCM3200 output ports.  

Be sure to add the loads for the devices you are using in your custom system and verify 

that they do not exceed the values in Table A-3.

Table A-2.  Capacitance of Rabbit 3000 I/O Ports

I/O Ports

Input 

Capacitance

(pF)

Output 

Capacitance

(pF)

Parallel Ports A to G

12

14

Table A-3.  External Capacitive Bus Loading -40°C to +70°C

Output Port

Clock Speed 

(MHz)

Maximum External 

Capacitive Loading (pF)

All I/O lines with clock 

doubler enabled

29.4

30–70

All I/O lines with clock 

doubler disabled

14.7456

100