09.12.2012 Views

RM0090: Reference manual - STMicroelectronics

RM0090: Reference manual - STMicroelectronics

RM0090: Reference manual - STMicroelectronics

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Debug support (DBG) <strong>RM0090</strong><br />

Figure 425. SWJ debug port<br />

JTDO<br />

JTDI<br />

NJTRST<br />

JTMS/SWDIO<br />

JTCK/SWCLK<br />

TRACESWO (asynchronous trace)<br />

SWJ-DP<br />

TDO<br />

TDI<br />

nTRST<br />

SWD/JTAG<br />

select<br />

SWDITMS<br />

SWDO<br />

SWDOEN<br />

SWCLKTCK<br />

Figure 425 shows that the asynchronous TRACE output (TRACESWO) is multiplexed with<br />

TDO. This means that the asynchronous trace can only be used with SW-DP, not JTAG-DP.<br />

33.3.1 Mechanism to select the JTAG-DP or the SW-DP<br />

By default, the JTAG-Debug Port is active.<br />

If the debugger host wants to switch to the SW-DP, it must provide a dedicated JTAG<br />

sequence on TMS/TCK (respectively mapped to SWDIO and SWCLK) which disables the<br />

JTAG-DP and enables the SW-DP. This way it is possible to activate the SWDP using only<br />

the SWCLK and SWDIO pins.<br />

This sequence is:<br />

1. Send more than 50 TCK cycles with TMS (SWDIO) =1<br />

2. Send the 16-bit sequence on TMS (SWDIO) = 0111100111100111 (MSB transmitted<br />

first)<br />

3. Send more than 50 TCK cycles with TMS (SWDIO) =1<br />

33.4 Pinout and debug port pins<br />

The STM32F4xx MCUs are available in various packages with different numbers of<br />

available pins. As a result, some functionality (ETM) related to pin availability may differ<br />

between packages.<br />

1369/1416 Doc ID 018909 Rev 3<br />

TDO<br />

TDI<br />

nTRST<br />

TCK<br />

TMS<br />

DBGDI<br />

DBGDO<br />

DBGDOEN<br />

DBGCLK<br />

JTAG-DP<br />

nPOTRST<br />

nPOTRST<br />

DBGRESETn<br />

SW-DP<br />

From<br />

power-on<br />

reset<br />

ai17139

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!