AN2131QC Cypress Semiconductor Corp, AN2131QC Datasheet - Page 21

• Manufacturer Part Number: AN2131QC
• Description: IC MCU 8051 8K RAM 24MHZ 80BQFP
• Manufacturer: Cypress Semiconductor Corp
• Series: EZ-USB®r

Specifications of AN2131QC

• 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: 24
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 80-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1307

In this manual, you will read statements like, “When the host sends an IN token...” or “The
device responds with an ACK.” What do these terms mean? A USB transaction consists
of data packets identified by special codes called Packet IDs or PIDs. A PID signifies
what kind of packet is being transmitted. There are four PID types, as shown in Table 1-1.
Figure 1-3 illustrates a USB transfer. Packet j is an OUT token, indicated by the OUT
PID. The OUT token signifies that data from the host is about to be transmitted over the
bus. Packet !k contains data, as indicated by the DATA1 PID. Packet l is a handshake
packet, sent by the device using the ACK (acknowledge) PID to signify to the host that the
device received the data error-free.
Continuing with Figure 1-3, a second transaction begins with another OUT token m, fol-
lowed by more data n, this time using the DATA0 PID. Finally, the device again indicates
success by transmitting the ACK PID in a handshake packet o.
Why two DATA PIDs, DATA0 and DATA1? It’s because the USB architects took error
correction very seriously. As mentioned previously, the ACK handshake is a signal to the
host that the peripheral received data without error (the CRC portion of the packet is used
to detect errors). But what if a handshake packet itself is garbled in transmission? To
detect this, each side, host and device maintains a data toggle bit, which is toggled
between data packet transfers. The state of this internal toggle bit is compared with the
Page 1-4
1.4
Token Packet
O
U
T
Tokens and PIDs
A
D
D
R
1
E
N
D
P
C
R
C
5
D
A
T
A
1
Data Packet
Payload
Data
Token Data
Handshake
Special
2
PID Type
Chapter 1. Introducing EZ-USB
C
R
C
1
6
Figure 1-3. USB Packets
IN, OUT, SOF, SETUP, DATA0, DATA1
ACK, NAK, STALL
PRE
Table 1-1. USB PIDs
H/S Pkt
3
A
C
K
PID Name
Token Packet
O
U
T
A
D
D
R
4
E
N
D
P
C
R
C
5
D
A
T
A
0
Data Packet
Payload
Data
5
EZ-USB TRM v1.9
C
R
C
1
6
H/S Pkt
A
C
K
6