COM20022V-HT データシートの表示（PDF） - SMSC -> Microchip

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COM20022V-HT

10Mbps ARCNET controller with 2Kx8 on-board RAM

SMSC -> Microchip 

Table 13 – Bus Control Register

BIT

BIT NAME

SYMBOL

DESCRIPTION

4 Terminal Count

Bit 8

Refresh

Synchronous

Gate Time

TC8/

RSYN/

GTTM

The function of this bit is mode dependent. TC8 is for Non-

burst or burst mode. RSYN and GTTM are for the two

Programmable-Burst modes. RSYN is for External Re-

Trigger mode. GTTM is for internal Re-Trigger mode.

Non-burst or burst mode:

TC8: Bit 8 (MSB) of 9 bit Terminal Count setting register.

The other 8 bits are in the DMA Count register. Terminal

Count setting register is ignored when ITCEN = 0.

Programmable-Burst and External Re-Trigger mode:

RSYN = 0: DMA is started Immediately.

RSYN = 1: DMA is started after Refresh execution.

Programmable-Burst and Internal Re-Trigger mode:

GTTM = 0: Gate Time is 350nS (min)

GTTM = 1: Gate Time is 750nS (min)

3,2 DMA Transfer Mode DMAMD1, These bits select the data transfer mode of the DMA. These

DMAMD0 transfer modes influence the timing of asserting/negating the

DREQ pin.

DMAMD1 DMAMD0 Transfer Mode

0

0

Non-Burst (Default)

0

1

Burst

1

0

Programmable-Burst by Timer

1 TC Polarity

TCPOL

1

1

Programmable-Burst by Cycle

Counter

This bit sets the Active polarity of TC pin.

TCPOL = 0: Active High (Default), TCPOL = 1 Active Low

0 DREQ Polarity

DRQPOL

This bit sets the Active polarity of DREQ pin.

DRQPOL = 0: Active High (Default), DRQPOL = 1 Active

Low

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