RF60 Datasheet, PDF (151/157 Pages) –

RF60 CRYSTAL-LESS SOC TRANSMITTER v1.0
34. C2 Interface
The devices include an on-chip 2-Wire (C2) debug interface in-system debugging with the production part
installed in the end application. The C2 interface uses a clock signal (C2CLK) and a bi- directional C2 data
signal (C2DAT) to transfer information between the device and a host system. The C2 interface is intended
to be used by the third party development tools. It is not intended to be used for any other purpose. It can
be completely disabled per user programming for fully programmed chips.
34.1. C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging. 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 C2CLK (GPIO[5]) and C2DAT (GPIO[4]) 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 34.1 along with the connection to the standard 10-pin debugging interface header.
If pushbutton on keyfob
development board, then it
has to be isolated by R5
SW_GPIO4 _R5
1k5
VDD
For debugging chain to
work, LED must be
LED
isolated by R6
R6 470
VDD
VDD
50k
C2DAT ^GPIO4
C2CLK
Device
VDD
GPIO5
50k
USB debug adapter
10 pin header connector
1mA max
1k
R4
1
2
3
4
R1
TMS
C2CLK
5
7
6
8
1k
VBUS (~ +4.6V) ^{Can be used to}
9
generate local VDD
1k
R2
GPIO[4]
For application bidirectional use,
isolated from the C2
Figure 34.1. 10-pin C2 USB Debugging Adapter Connection to Device
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