AN2135SC Cypress Semiconductor Corp, AN2135SC Datasheet - Page 25

• Manufacturer Part Number: AN2135SC
• Description: IC MCU 8051 8K RAM 24MHZ 44QFP
• Manufacturer: Cypress Semiconductor Corp
• Series: EZ-USB®r

Specifications of AN2135SC

• Applications: USB Microcontroller
• Core Processor: 8051
• Program Memory Type: ROMless
• Controller Series: AN213x
• Ram Size: 8K x 8
• Interface: I²C, USB
• Number Of I /o: 8
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 44-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1308

1.8.3 Isochronous Transfers
Isochronous data is time-critical and used for streaming data like audio and video. Time
of delivery is the most important requirement for isochronous data. In every USB frame, a
certain amount of USB bandwidth is allocated to isochronous transfers. To lighten the
overhead, isochronous transfers have no handshake (ACK/NAK/STALL), and no retries.
Error detection is limited to a 16-bit CRC. Isochronous transfers do not use the data tog-
gle mechanism; isochronous data uses only the DATA0 PID.
1.8.4 Control Transfers
Control transfers are used to configure and send commands to a device. Being mission
critical, they employ the most extensive error checking USB offers. Control transfers are
delivered on a best effort basis by the host (best effort is defined by a six-step process in
the Universal Serial Bus Specification Version 1.1, “Section 5.5.4”). The host reserves a
part of each USB frame time for Control transfers.
Page 1-8
Token Packet
Token Packet
Token Packet
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Figure 1-6. An Isochronous Transfer
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Figure 1-7. A Control Transfer
Chapter 1. Introducing EZ-USB
Data Pkt
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STATUS
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EZ-USB TRM v1.9