EM357-RTR Ember, EM357-RTR Datasheet - Page 108

• 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

EM351 / EM357
A DMA buffer’s end address, SCx_TXENDA/B (or SCx_RXENDA/B), can be written while the buffer is loaded or
active. This is useful for receiving messages that contain an initial byte count, since it allows software to set
the buffer end address at the last byte of the message.
As the DMA channel transfers data between the transmit or receive FIFO and a memory buffer, the DMA count
register contains the byte offset from the start of the buffer to the address of the next byte that will be
written or read. A transmit DMA channel has a single DMA count register (SCx_TXCNT) that applies to
whichever transmit buffer is active, but a receive DMA channel has two DMA count registers (SCx_RXCNTA/B),
one for each receive buffer. The DMA count register contents are preserved until the corresponding buffer, or
either buffer in the case of the transmit DMA count, is loaded, or until the DMA is reset.
The receive DMA count register may be written while the corresponding buffer is loaded. If the buffer is not
loaded, writing the DMA count register also loads the buffer while preserving the count value written. This
feature can simplify handling UART receive errors.
The DMA channel stops using a buffer and unloads it when the following is true:
(DMA buffer start address + DMA buffer count) > DMA buffer end address
Typically a transmit buffer is unloaded after all its data has been sent, and a receive buffer is unloaded after
it is filled with data, but writing to the buffer end address or buffer count registers can also cause a buffer to
unload early.
Serial controller DMA channels include additional features specific to the SPI and UART operation and are
described in those sections.
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120-035X-000G
Final