AS7221 datasheet(17/36 Pages) AMSCO

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[v1-01] 2016-Dec-08

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AS7221 − Detailed Description

UART and Smart Lighting Command Interface

The UART block implements the TX and RX signals as defined

in the RS-232 / V.24 standard communication protocol.

UART Feature List

• Full Duplex Operation (Independent Serial Receive and

Transmit Registers) with FIFO buffer of 8 bytes for each.

• Factory set to 115.2k Baud

• Supports Serial Frames with 8 Data Bits, no Parity and

1 Stop Bit.

Operation

Transmission

If data is available in the transmit FIFO, it will be moved into the

output shift register and the data will be transmitted at the

configured Baud Rate, starting with a Start Bit (logic zero) and

followed by a Stop Bit (logic one).

Reception

At any time, with the receiver being idle, if a falling edge of a

start bit is detected on the input, a byte will be received and

stored in the receive FIFO. The following Stop Bit will be checked

to be logic one.

Figure 20:

UART Protocol

Start Bit

Tbit=1/Baude Rate

Stop Bit

Next Start

Sample Points

Start Bit detected

After Tbit/2: Sampling of Start Bit

After Tbit: Sampling of Data

Always Low

Always High

Data Bits

AS7221 데이터시트(PDF) 17 Page - ams AG