EM357-RTR datasheet(24/241 Pages) SILABS

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Rev 1.3

or 12 MHz when using the high-frequency internal RC oscillator.

The EM351 has 128 kB of flash memory and the EM357 has 192 kB of flash memory. Both chips have 12 kB of

RAM on-chip, and the ARM configurable memory protection unit (MPU).

The EM35x implements both the ARM Serial Wire and JTAG debug interfaces. These interfaces provide real time,

non-intrusive programming and debugging capabilities. Serial Wire and JTAG provide the same functionality, but

are mutually exclusive. The Serial Wire interface uses two pins; the JTAG interface uses five. Serial Wire is

preferred, since it uses fewer pins.

The EM35x contains 24 GPIO pins shared with other peripheral or alternate functions. Because of flexible routing

within the EM35x, external devices can use the alternate functions on a variety of different GPIOs. The integrated

serial controller SC1 can be configured for SPI (master or slave), TWI (master-only), or UART operation, and the

serial controller SC2 can be configured for SPI (master or slave) or TWI (master-only) operation.

The EM35x has a general purpose ADC which can sample analog signals from six GPIO pins in single-ended or

differential modes. It can also sample the 1.8 V regulated supply VDD_PADSA, the voltage reference VREF, and

GND. The ADC has one voltage range: 0 to 1.2 V (normal). The ADC has a DMA mode to capture samples and

automatically transfer them into RAM. The integrated voltage reference for the ADC, VREF, can be made available

to external circuitry. An external voltage reference can also be driven into the ADC. The regulator input voltage,

VDD_PADS, cannot be measured using the general purpose ADC, but it can be measured through Ember

software.

The EM35x contains four oscillators: a high-frequency 24 MHz external crystal oscillator, a high-frequency 12 MHz

internal RC oscillator, an optional low-frequency 32.768 kHz external crystal oscillator, and a low-frequency 10 kHz

internal RC oscillator.

The EM35x has an ultra low power, deep sleep state with a choice of clocking modes. The sleep timer can be

clocked with either the external 32.768 kHz crystal oscillator or with a 1 kHz clock derived from the internal 10 kHz

RC oscillator. Alternatively, all clocks can be disabled for the lowest power mode. In the lowest power mode, only

external events on GPIO pins will wake up the chip. The EM35x has a fast startup time (typically 110 µs) from deep

sleep to the execution of the first ARM® CortexTM-M3 instruction.

The EM35x contains three power domains. The always-on high voltage supply powers the GPIO pads and critical

chip functions. Regulated low voltage supplies power the rest of the chip. The low voltage supplies are disabled

during deep sleep to reduce power consumption. Integrated voltage regulators generate regulated 1.25 V and

1.8 V voltages from an unregulated supply voltage. The 1.8 V regulator output is decoupled and routed externally

to supply analog blocks, RAM, and flash memories. The 1.25 V regulator output is decoupled externally and

supplies the core logic.

Note:

The EM35x is not pin-compatible with the previous generation chip, the EM250, except for the RF section of the chip.

Pins 1-11 and 45-48 are compatible, to ease migration to the EM35x.

EM357-RTR 数据表(PDF) 24 Page - Silicon Laboratories

EM357-RTR 数据表(HTML) 24 Page - Silicon Laboratories

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