AN2136SC Cypress Semiconductor Corp, AN2136SC Datasheet - Page 82

• Manufacturer Part Number: AN2136SC
• Description: IC MCU 8051 8K RAM 24MHZ 44QFP
• Manufacturer: Cypress Semiconductor Corp
• Series: EZ-USB®r

Specifications of AN2136SC

• 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: 428-1309

When the EZ-USB chip comes out of reset, the EZ-USB core makes a decision about how
to enumerate based on the contents of an external EEPROM on its I
shows the choices. In Table 5-5, PID means Product ID, VID means Version ID, and DID
means Device ID.
If no EEPROM is present, or if one is present but the first byte is neither 0xB0 nor 0xB2,
the EZ-USB core enumerates using internally stored descriptor data, which contains the
Cypress Semiconductor VID, PID, and DID. These ID bytes cause the host operating sys-
tem to load a Cypress Semiconductor device driver. The EZ-USB core also establishes the
Default USB device. This mode is only used for code development and debug.
If a serial EEPROM is attached to the I
enumerates with the same internally stored descriptor data as for the no-EEPROM case,
but with one difference. It supplies the PID/VID/DID data from six bytes in the external
EEPROM rather than from the EZ-USB core. The custom VID/PID/DID in the EEPROM
causes the host operating system to load a device driver that is matched to the EEPROM
VID/PID/DID. This EZ-USB operating mode provides a soft USB device using ReNu-
meration
If a serial EEPROM is attached to the I
transfers the contents of the EEPROM into internal RAM. The EZ-USB core also sets the
ReNum bit to 1 to indicate that the 8051 (and not the EZ-USB core) responds to device
requests over CONTROL endpoint zero (see the text box, “When ReNum=1 at Power-
On” on page 5-6). Therefore, all descriptor data, including VID/DID/PID values, are sup-
plied by the 8051 firmware. The last byte loaded from the EEPROM (to the CPUCS reg-
ister) releases the 8051 reset signal, allowing the EZ-USB chip to come up as a fully
custom device with firmware in RAM.
The following sections discuss these enumeration methods in detail.
EZ-USB TRM v1.9
5.5
Enumeration Modes
Not 0xB0 or 0xB2
0xB0
0xB2
First EEPROM byte
Table 5-5. EZ-USB Core Action at Power-Up
Supplies descriptors, PID/VID/DID from EZ-USB
Core. Sets ReNum=0.
Supplies descriptors from EZ-USB core, PID/VID/DID
from EEPROM. Sets ReNum=0.
Loads EEPROM into EZ-USB RAM. Sets ReNum=1;
therefore 8051 supplies descriptors, PID/VID/DID.
Chapter 5. EZ-USB CPU
2
2
C bus and its first byte is 0xB0, the EZ-USB core
C bus and its first byte is 0xB2, the EZ-USB core
EZ-USB Core Action
2
C bus. Table 5-5
Page 5-7