Zilog Z16C30 Instrukcja Użytkownika Pobierz pdf (Strona 107)

5-40

Z16C30 USC

USER'S MANUAL

UM97USC0100

ZILOG

5.20 COMMANDS

Commands are encoded values that software writes to a

perform some action. Typically commands don’t take any

software-perceptible time to perform. USC command fields

are write-only; reading them back may yield zeroes or

some unrelated status item.

Often commands represent a more compact and efficient

way to provide control features than dedicated register

bits. In fact, commands are so popular that each USC

channel includes three separate encoded command fields!

Figure 5-19 shows the Channel Command/Address Reg-

ister. Software can write various commands that affect the

Transmitter and/or the Receiver to its RTCmd field

(CCAR15-11). In addition, software can write commands

that affect the Transmitter to the TCmd field in the Transmit

Command/Status Register (TCSR15-12), and can write

commands that affect the Receiver to the RCmd field in the

Receive Command/Status Register (RCSR15-12).

Writing all zeroes to any of the command fields does

nothing, which can be useful when the intent is to write to

other fields of the register. Zilog reserves other values not

listed below for future extensions to the USC family; such

values should not be written to the subject field.

RTCmd

Value Function

00010 Reset Highest Serial IUS

00100 Trigger Channel Load DMA

00101 Trigger Rx DMA

00110 Trigger Tx DMA

00111 Trigger Rx and Tx DMA

01001 Purge Rx FIFO

01010 Purge Tx FIFO

01011 Purge Rx and Tx FIFO

01101 Load RCC

01110 Load TCC

01111 Load RCC and TCC

10001 Load TC0

10010 Load TC1

10011 Load TC0 and TC1

10100 Select Serial LSBit First

10101 Select Serial MSBit First

10110 Select D15-8 First

10111 Select D7-0 First

11001 Purge Rx

TCmd

Value Function

0010 Clear Tx CRC Generator

0101 Select TICRHi=FIFO Status

0110 Select TICRHi=/INT Level

0111 Select TICRHi=/TxREQ Level

1000 Send Frame/Message

1001 Send Abort

1100 Enable DLE Insertion

1101 Disable DLE Insertion

1110 Clear EOF/EOM

1111 Set EOF/EOM

RCmd

Value Function

0010 Clear Rx CRC Generator

0011 Enter Hunt Mode

0101 Select RICRHi=FIFO Status

0110 Select RICRHi=/INT Level

0111 Select RICRHi=/RxREQ Level

UM009402-0201

1 2 ... 102 103 104 105 106 107 108 109 110 111 112 ... 207 208

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