ZLP12840 datasheet(56/58 Pages) ZILOG

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PS024406-0106

P R E L I M I N A R Y

Operation

ZLP12840 OTP MCU

Product Specification

Transmitting Data Using the Polled Method

Follow the steps below to transmit data using the polled method of operation:

1. Write to the baud rate generator constant (BCNST) register, address ðÚì¸, to set the

appropriate baud rate.

2. Write a 0 to bit 6 of the P01M register.

3. Write to the UART control register (UCTL) to:

a. Set the transmit enable bit, UCTL[7], to enable the UART for data transmission.

b. If parity is appropriate, set the parity enable bit, UCTL[4] to 1 and select either

Even or Odd parity (UCTL[3]).

4. Check the Transmit Status register bit, UST[2], to determine if the Transmit Data reg-

ister is empty (indicated by a 1). If empty, continue to Step 6. If the Transmit Data reg-

ister is full (indicated by a 0), continue to monitor the UST[2] bit until the Transmit

Data register becomes available to receive new data.

5. Write the data byte to the UART Transmit Data register, ðÚï¸. The transmitter auto-

matically transfers the data to the internal transmit shift register and transmits the data.

6. To transmit additional bytes, return to Step 4.

Figure 14. UART Asynchronous Data Format without Parity

Figure 15. UART Asynchronous Data Format with Parity

lsb

msb

Idle state

of line

Stop bit(s)

Data field

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

Start

lsb

msb