
EM358x
54
Rev. 0.4
Table 7-2. Timer 2 Output Configuration Controls
Timer 2 Output
Option Register Bit
GPIO Mapping Selected by TIM2_OR Bit
0
1
TIM2C1
TIM2_OR[4]
PA0
PB1
TIM2C2
TIM2_OR[5]
PA3
PB2
TIM2C3
TIM2_OR[6]
PA1
PB3
TIM2C4
TIM2_OR[7]
PA2
PB4
For outputs assigned to the serial controllers, the serial interface mode registers (SCx_MODE) determine how the
GPIO pins are used.
The alternate outputs of PA4 and PA5 can either provide packet trace data (PTI_EN and PTI_DATA), or
synchronous CPU trace data (TRACEDATA2 and TRACEDATA3). The selection of packet trace or CPU trace is
made through the Ember software.
The alternate outputs of PB0 and PC1 can also provide TRACEDATA2 and TRACEDATA3 for situations where
packet trace is also required.
If a GPIO does not have an associated peripheral in alternate output mode, its output is set to 0.
7.3 Forced Functions
For some GPIOs the GPIO_PxCFGH/L configuration will be overridden. These functions are forced when the
EM358x is reset and remain forced until software or an external debugger overrides the forced functions. Table
7-3 shows the GPIOs that have different functions forced on them regardless of the GPIO_PxCFGH/L registers.
Table 7-3. GPIO Forced Functions
GPIO Forced Mode
Forced Signal
PA7 Open-drain output
REG_EN
PC0 Input with pull up
JRST
PC2 Push-pull output
JTDO
PC3 Input with pull up
JDTI
PC4
1
Input with pull up
JTMS
PC4
1
Bidirectional (push-pull output or floating input) controlled by debugger interface SWDIO
1
The choice of PC4’s forced signal is normally controlled by an external debug tool. JTMS is forced when the SWJ is in JTAG mode and
SWDIO is forced when the SWJ is in Serial Wire mode. But, when GPIO_DEBUGDIS is set and PC4 is configured in SWDIO mode, then
SWDIO is the only functionality available on PC4.
PA7 is forced to be the regulator enable signal, REG_EN. If an external regulator is used and controlled through
REG_EN, PA7’s forced functionality must not be overridden. If an external regulator is not used, REG_EN may be
disabled and PA7 may be reclaimed as a normal GPIO. Disabling REG_EN is done by clearing the bit
GPIO_EXTREGEN in the GPIO_DBGCFG register.
PC0, PC2, PC3, and PC4 are forced to be the Serial Wire and JTAG (SWJ) Interface. When the EM358x resets,
these four GPIOs are forced to operate in JTAG mode. Switching the debug interface between JTAG mode and
Serial Wire mode can only be accomplished by the external debug tool and cannot be affected by software
executing on the EM358x.
It is possible to either reclaim all of the four debugger pins (PC0, PC2, PC3, and P4), or reclaim the JTAG only
debugger pins (PC0, PC2, and PC3) leaving Serial Wire operational.
Summary of Contents for EMBER EM358 series
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