Z85C3008VSG Zilog, Z85C3008VSG Datasheet - Page 256

• Manufacturer Part Number: Z85C3008VSG
• Description: IC 8MHZ Z8500 CMOS SCC 44-PLCC
• Manufacturer: Zilog
• Series: SCCr

Specifications of Z85C3008VSG

• Processor Type: Z80
• Features: Error Detection and Multiprotocol Support
• Speed: 8MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 44-LCC (J-Lead)
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Cpu Speed: 8MHz
• Digital Ic Case Style: LCC
• No. Of Pins: 44
• Supply Voltage Range: 5V
• Operating Temperature Range: 0°C To +70°C
• Svhc: No SVHC (18-Jun-2010)
• Base Number: 85
• Rohs Compliant: Yes
• Clock Frequency: 8MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 269-3932; Z85C3008VSG

UM010901-0601
TRANSMIT FIFO INTERRUPT
In the ESCC, transmit interrupt frequencies are reduced by
a deeper Transmit FIFO and the revised transmit interrupt
structure. If the WR7' D5 Transmit FIFO Interrupt Level bit
is reset, the transmit interrupt is generated when the entry
location of the FIFO is empty, i.e., more data can be
written. This is downward compatible with a SCC Transmit
Interrupt since the SCC only has a one-byte transmit buffer
instead of a four-byte Transmit FIFO.
Figure 4. Flowchart of Transmit Interrupt Service Routine to Reduce Transmit Interrupt Frequencies
Transmit FIFO
Transmit FIFO
With Data
Is Loaded
Full
NO
Boost Your System Performance Using The Zilog ESCC
TBE Interrupt
Transmit FIFO
Write Data To
Level Enabled
If WR7' D5 is set, the transmit buffer empty interrupt is
generated when the transmit FIFO is completely empty.
Enabling the transmit FIFO interrupt level, together with
polling the Transmit Buffer Empty (TBE) bit in RR0, causes
significant transmit interrupt frequency reduction. Transmit
data is sent in blocks of four bytes (algorithm is illustrated
in Figure 4). This helps to offload those systems which
have long interrupt latency or a fully loaded Operating
System.
TX FIFO Int.
TBE = '1'?
Service
RR0
YES
Application Note
6-121
™
1