![Silicon Laboratories EFR32xG14 Wireless Gecko Скачать руководство пользователя страница 627](http://html1.mh-extra.com/html/silicon-laboratories/efr32xg14-wireless-gecko/efr32xg14-wireless-gecko_reference-manual_1271728627.webp)
19.3.11 Pulse Generator/ Pulse Extender
The LEUART has an optional pulse generator for the transmitter output, and a pulse extender on the receiver input. These are enabled
by setting PULSEEN in LEUARTn_PULSECTRL, and with INV in LEUARTn_CTRL set, they will change the output/input format of the
LEUART from NRZ to RZI as shown in
Figure 19.11 LEUART - NRZ vs. RZI on page 627
.
S
0
1
2
3
4
5
6
7
P
Stop
Idle
Idle
NRZ
RZI
Figure 19.11. LEUART - NRZ vs. RZI
If PULSEEN in LEUARTn_PULSECTRL is set while INV in LEUARTn_CTRL is cleared, the output waveform will look like RZI shown in
Figure 19.11 LEUART - NRZ vs. RZI on page 627
The width of the pulses from the pulse generator can be configured using PULSEW in LEUARTn_PULSECTRL. The generated pulse
width is 1 cycles of the 32.768 kHz clock, which makes pulse width from 31.25µs to 500µs possible.
Since the incoming signal is only sampled on positive clock edges, the width of the incoming pulses must be at least two 32.768 kHz
clock periods wide for reliable detection by the LEUART receiver. They must also be shorter than half a UART bit period.
At 2400 baud or lower, the pulse generator is able to generate RZI pulses compatible with the IrDA physical layer specification. The
external IrDA device must generate pulses of sufficient length for successful two-way communication.
PULSEFILT in the LEUARTn_PULSECTRL register can be used to extend the minimum receive pulse width from 2 clock periods to 3
clock periods.
19.3.11.1 Interrupts
The interrupts generated by the LEUART are combined into one interrupt vector. If LEUART interrupts are enabled, an interrupt will be
made if one or more of the interrupt flags in LEUARTn_IF and their corresponding bits in LEUART_IEN are set.
19.3.12 Register Access
Since this module is a Low Energy Peripheral, and runs off a clock which is asynchronous to the HFCORECLK, special considerations
must be taken when accessing registers. Refer to
4.3 Access to Low Energy Peripherals (Asynchronous Registers)
for a description on
how to perform register accesses to Low Energy Peripherals.
The registers LEUARTn_FREEZE and LEUARTn_SYNCBUSY are used for synchronization of this peripheral.
Reference Manual
LEUART - Low Energy Universal Asynchronous Receiver/Transmitter
silabs.com
| Building a more connected world.
Rev. 1.1 | 627