EM357-RTR Ember, EM357-RTR Datasheet - Page 127

• Manufacturer Part Number: EM357-RTR
• Description: IC RF TXRX ZIGBEE 192KB 48QFN
• Manufacturer: Ember

Specifications of EM357-RTR

• Frequency: 2.4GHz
• Data Rate - Maximum: 250kbps
• Modulation Or Protocol: 802.15.4 Zigbee
• Applications: General Purpose
• Power - Output: 5dBm
• Sensitivity: -100dBm
• Voltage - Supply: 2.1 V ~ 3.6 V
• Current - Receiving: 26mA
• Current - Transmitting: 31mA
• Data Interface: PCB, Surface Mount
• Memory Size: 192kB Flash, 12kB RAM
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 636-1011-2

9.2 GPIO Usage
9.3 Timer Functional Description
The timers can optionally use GPIOs in the PA and PB ports for external inputs or outputs. As with all EM35x
digital inputs, a GPIO used as a timer input can be shared with other uses of the same pin. Available timer
inputs include an external timer clock, a clock mask, and four input channels. Any GPIO used as a timer output
must be configured as an alternate output and is controlled only by the timer.
Many of the GPIOs that can be assigned as timer outputs can also be used by another on-chip peripheral such
as a serial controller. Using a GPIO as a timer output takes precedence over another peripheral function, as
long as the channel is configured as an output in the TIMx_CCMR1 register and is enabled in the TIMx_CCER
register.
The GPIOs that can be used by Timer 1 are fixed, but the GPIOs that can be used as Timer 2 channels can be
mapped to either of two pins, as shown in Table 9-1. The Timer 2 Option Register (TIM2_OR) has four single
bit fields (TIM_REMAPCy) that control whether a Timer 2 channel is mapped to its default GPIO in port PA, or
remapped to a GPIO in PB.
Table 9-1 specifies the pins that may be assigned to Timer 1 and Timer 2 functions.
The TIMxCLK and TIMxMSK inputs can be used only in the external clock modes; refer to the External Clock
Source Mode 1 and External Clock Source Mode 2 sections for details concerning their use.
9.3.1
The main block of the general purpose timer is a 16-bit counter with its related auto-reload register. The
counter can count up, down, or alternate up and down. The counter clock can be divided by a prescaler.
The counter, the auto-reload register, and the prescaler register can be written to or read by software. This is
true even when the counter is running.
The time-base unit includes:
Some timer registers cannot be directly accessed by software, which instead reads and writes a “buffer
register”. The internal registers actually used for timer operations are called “shadow registers”.
The auto-reload register is buffered. Writing to or reading from the auto-reload register accesses the buffer
register. The contents of the buffer register are transferred into the shadow register permanently or at each
Timer 1
Timer 2
(TIM_REMAPCy = 0)
Timer 2
(TIM_REMAPCy = 1)
Counter Register (TIMx_CNT)
Prescaler Register (TIMx_PSC)
Auto-Reload Register (TIMx_ARR)
(direction)
Signal
Time-Base Unit
(in or out)
TIMxC1
PB6
PA0
PB1
(in or out)
TIMxC2
Table 9-1. Timer GPIO Usage
PB7
PA3
PB2
Final
9-3
(in or out)
TIMxC3
PA6
PA1
PB3
(in or out)
TIMxC4
PA7
PA2
PB4
EM351 / EM357
TIMxCLK
PB0
PB5
PB5
(in)
120-035X-000G
TIMxMSK
PB5
PB0
PB0
(in)