COM20022V-HT View Datasheet(PDF) - SMSC -> Microchip

Part Name

Description

Manufacturer

COM20022V-HT

10Mbps ARCNET controller with 2Kx8 on-board RAM

SMSC -> Microchip 

The use of the TC8/RSYN/GTTM bit is also

transfer mode dependent. TC8 is bit 8 of the

Terminal Count register. RSYN is the refresh

synchronous bit; it is used to select whether the

DMA is started immediately or after Refresh

execution. GTTM is the Gate Time bit; it is used

to select the gate time of the Programmable-

Burst transfer.

TC8 is for Non-Burst or Burst mode. RSYN and

GTTM are for the two Programmable-Burst

modes.

The W16 bit is used to enable/disable the 16 bit

access.

DMA COUNT REGISTER

The DMA COUNT Register is new to the

COM20022. It is an 8-bit read/write register

accessed when the Sub Address Bits SUBAD[2:0]

are set up accordingly (see the bit definitions of

the Sub Address Register). This register contains

bits for control of the DMA functionality. The

TC7-TC0 /TIM7-TIM0 /CYC7-CYC0 bits have

one of three functions depending on the DMA

transfer mode. TC7-TC0 are for Non-Burst or

Burst mode. These are the lower 8 bits of the

Terminal Count setting register (the MSB is in

the Bus Control Register). The TIM7-TIM0 bits

are for setting the time of the continuous DMA

transfer in Programmable-Burst by Timer mode.

The CYC7-CYC0 bits are for setting the cycle

count value of the continuous DMA transfer in

Programmable-Burst by cycle mode.

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