AN958: Debugging and Programming
Interfaces for Custom Designs
The Silicon Labs MCU and Wireless Starter Kits and Simplicity
Studio provide a powerful development and debug environment.
In order to take advantage of these capabilities and features on custom hardware, Sili-
con Labs recommends including debugging and programming interface connector(s) in
custom hardware designs. Possible options include full support of all debugging and
programming capabilities of the STK, to serial wire programming only. This application
note describes the benefits of including these connector interfaces in custom hardware
designs and provides the details regarding these interfaces.
KEY POINTS
• Wireless starter kits along with Simplicity
Studio provide a powerful development
and debug environment
• Use the debugging and programming
interface connector(s) to take advantage of
these capabilities
Simplicity Debug Adapter Board
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AN958: Debugging and Programming Interfaces for Custom Designs
Background
1. Background
The Silicon Labs MCU Starter Kit (STK) and Wireless Starter Kit (WSTK) provide a powerful development and debug environment
when used with Simplicity Studio. The STK and WSTK provide several debug capabilities and features, including the following:
• SWD (serial wire debug)
• 2-pin serial wire debug interface for programming and debugging, using the pins SWCLK and SWDIO.
• JTAG
• 4-wire interface for programming and debugging, using the pins TCK, TMS, TDI, and TDO.
• C2 interface (for 8-bit devices)
• 2-wire programming interface used by most Silicon Labs 8-bit MCUs.
• See "AN124: Pin Sharing Techniques for the C2 Interface", which discusses pin sharing for C2 devices.
• ETM* (embedded trace macrocell)
• Debug component which enables reconstruction of program execution, and is designed as a high-speed, low-power debug tool
that only supports instruction trace.
• AEM (advanced energy monitoring)
• Accurate high-speed current measurements and energy debugging/profiling when the STK/WSTK power selection switch is in the
AEM position. Use with Simplicity Studio Energy Profiler perspective.
• PTI (packet trace interface [WSTK only])
• Physical layer (PHY) level PTI for effective network-level debugging. Monitors all the PHY transmit and receive packets between
the MAC and baseband modules within the radio without affecting normal operation.
• VCOM (virtual COM port)
• UART COM port interface to the target from the debugger (pass-through UART).
• Virtual UART
• SWD-based virtual UART interface to the target from the debugger, available through the SWD interface (SWDIO, SWCLK, and
SWO).
These features are available via several different interface means, depending on the features required by the custom target hardware
design and the board space available for these interface connectors or test points. These details are discussed in the following sec-
tions.
*Note:
The STK and WSTK support ETM only when using an external debugger which supports ETM Capture. The STK and WSTK do
not include an ETM capture unit. Only devices that have an ETM macrocell will support ETM capture, regardless of the debugger capa-
bilities. Consult the corresponding MCU or Wireless device data sheet for details regarding whether ETM is supported on the device.
Silicon Labs MCU and Wireless Development Kits may include support for ETM. Consult the kit documentation for further details.
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AN958: Debugging and Programming Interfaces for Custom Designs
Interface Feature Mapping
2. Interface Feature Mapping
The table below summarizes the capabilities and features of the various interfaces described in the following sections. Click on the col-
umn header hyperlinks to go directly to the section describing each specific interface.
Table 2.1. Interface Capabilities and Features
Feature
20-pin Standard
ARM Cortex
Debug+ETM
Connector
20-pin
Simplicity
Connector
Simplicity Debug Adapter Board Interfaces
(Standard or Tag-Connect 10-pin cable)
Mini
Simplicity
Connector
X
Cortex Debug
Connector
X
X
X
ISA3 Packet
Trace Port
Connector
1
X
X
Tag-Connect
6-pin
Interface
SWD (serial wire debug)
JTAG
C2
ETM (embedded trace
module)
AEM (advanced energy
monitoring)
PTI (packet trace interface)
VCOM (virtual COM port)
Virtual UART
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Note:
1. ISA3 Packet Trace Port Connector interface is not yet supported by the WSTK.
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AN958: Debugging and Programming Interfaces for Custom Designs
Connector Interfaces
3. Connector Interfaces
This section presents the standard debug connector interfaces provided by the STK and WSTK, as well as recommendations for includ-
ing connector interfaces on custom target hardware designs in order to utilize these debug capabilities and features.
3.1 Standard ARM Cortex Debug+ETM Connector
In cases where ETM and/or JTAG debug capabilities and features are required on custom target hardware, a 20-pin (2x10, 1.27 mm
pitch) standard ARM Cortex Debug+ETM Connector (similar to Sullins
™
part number GRPB102VWQS) should be included in the de-
sign. A 20-pin 2x10 1.27 mm pitch ribbon cable (similar to Samtec
™
part number FFSD-10-D-6.00-01-N) is required for the connection
between the WSTK debug connector and the custom target hardware board connector.
Note:
Silicon Labs deviates slightly from the ARM standard, as this version of the connector includes the key pin.
3.1.1 Connector Pin-Out
A pin-out for this debug connector interface is provided in the figure and table below. If ETM and/or JTAG are not required, see
4. Alternative Interfaces
for other debug interface options to include on target hardware designs.
VTARGET
GND
GND
NC
Cable Detect
NC
NC
GND
GND
GND
1
3
5
7
9
11
13
15
17
19
2
4
6
8
10
12
14
16
18
20
TMS / SWDIO / C2D
TCK / SWCLK / C2CK
TDO / SWO
TDI / C2Dps
RESET / C2CKps
TRACECLK
TRACED0
TRACED1
TRACED2
TRACED3
Figure 3.1. Debug Connector
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AN958: Debugging and Programming Interfaces for Custom Designs
Connector Interfaces
Table 3.1. Debug Connector Pin Descriptions
Pin Number(s)
1
2
4
6
8
10
12
14
16
18
20
9
11, 13
3, 5, 15, 17, 19
Function
VTARGET
TMS / SDWIO / C2D
TCK / SWCLK / C2CK
TDO/SWO
TDI / C2Dps
RESET / C2CKps
TRACECLK
TRACED0
TRACED1
TRACED2
TRACED3
Cable detect
NC
GND
Note
Target voltage on the debugged application
JTAG test mode select, Serial Wire data or C2 data
JTAG test clock, Serial Wire clock or C2 clock
JTAG test data out or Serial Wire Output
JTAG test data in, or C2D "pin sharing" function
1
Target device reset, or C2CK "pin sharing" function
Not connected
Not connected
Not connected
Not connected
Not connected
Connect to ground
Not connected
Note:
1. See "AN124: Pin Sharing Techniques for the C2 Interface", which discusses pin sharing for C2 devices.
3.1.2 Connector Footprint
An example component footprint is from Sullins for part number GRPB102VWQS. Refer to
http://www.sullinscorp.com/catalogs/
82_PAGE90-91_.050_MALE_HDR_ST_RA_SMT.pdf
for details on this connector footprint for the custom target hardware PCB.
3.2 20-pin Simplicity Connector
If AEM, PTI, and VCOM functionality are desired, include the 20-pin (2x10, 1.27 mm pitch) Simplicity Connector (similar to Sullins part
number GRPB102VWQS) on the target hardware design. A 20-pin 2 x 10 1.27 mm pitch ribbon cable (similar to Samtec part number
FFSD-10-D-6.00-01-N) is required for this connection between WSTK Simplicity connector and the custom target hardware board con-
nector. If space constraints do not allow inclusion of this connector on the target hardware design, see
4. Alternative Interfaces
for
smaller interfaces which provide similar debug features.
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