C8051F38C-GMR View Datasheet(PDF) - Silicon Laboratories

Part Name

Description

MFG CO.

C8051F38C-GMR

Full Speed USB Flash MCU Family

Silicon Laboratories 

C8051F380/1/2/3/4/5/6/7/C

28.2. C2 Pin Sharing

The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and

Flash programming may be performed. This is possible because C2 communication is typically performed

when the device is in the halt state, where all on-chip peripherals and user software are stalled. In this

halted state, the C2 interface can safely ‘borrow’ the C2CK (RST) and C2D pins. In most applications,

external resistors are required to isolate C2 interface traffic from the user application. A typical isolation

configuration is shown in Figure 28.1.

C8051Fxxx

RST (a)

Input (b)

Output (c)

C2CK

C2D

C2 Interface Master

Figure 28.1. Typical C2 Pin Sharing

The configuration in Figure 28.1 assumes the following:

1. The user input (b) cannot change state while the target device is halted.

2. The RST pin on the target device is used as an input only.

Additional resistors may be necessary depending on the specific application.

Rev. 1.4

319

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