CY7C64601

• Single-chip integrated USB Transceiver, Serial Interface Engine (SIE), and Enhanced 8051 Microprocessor
• Soft: 8051 runs from internal RAM, which is:
-Downloaded via USB, or
-Loaded from EEPROM
• 14 Bulk/Interrupt endpoints, each with a maximum packet size of 64 bytes
• 16 Isochronous endpoints, with 2 KB of buffer space (1 KB, double buffered) which may be divided among the sixteen isochronous endpoints
• Integrated, industry standard 8051 with enhanced features:
-Four clocks per cycle
-Two UARTS
-Three counter/timers
-Expanded interrupt system
-Two data pointers
• 3.3-volt operation
• Smart Serial Interface Engine (SIE)
• Vectored USB interrupts
• Separate buffers for the SETUP and DATA portions of a CONTROL transfer
• Integrated I2C™ controller
• 48-MHz or 24-MHz 8051 operation
• Enhanced IO
-IO port registers mapped to SFRs
-Port bits can be controlled using 8051 bit addressing instructions
• Four integrated general purpose 8-bit FIFOs
-64 bytes each
-Automatic conversion to and from 16-bit buses
-FIFOs can use externally supplied clock
-Easy interface to ASIC and DSP ICs
-Brings glue FIFOs inside for lower system cost
• DMA Controller
-Moves data between slave FIFOs, memory, and ports
-Very fast transfers-one clock (20.8 ns) per byte for internal transfers
-Can use external RAM as additional FIFO (addressed through A/D buses)
• Special Autovectors for DMA and FIFO interrupts
• 400-kHz or 100-kHz I2C operation
• General Programmable Interface (GPIF)
-Allows direct connection to most parallel interfaces: 8- and 16-bit
-Programmable Waveform Descriptors and Configuration Registers to define waveforms
-Supports multiple Ready (RDY) inputs and Control (CTL) outputs
• Three package options - 128-pin PQFP, 80-pin PQFP, and 52-pin PQFP

The EZ-USB FX,CY7C64601  has a weak internal pull-up resistor that is present on the inputs and outputs when the external signal level is a high (above 1.3V). The weak internal pull-up is not present in the circuit when the voltage level of the external signal is low. Since the weak pull-up is only in the CY7C64601  when the external signal level is high, this means that if the last voltage level driven on the pin was a high, the pull-up resistor will keep it high. However, if the last voltage level driven on the pin was a low then the pull-up is turned off and the pad can float until it gets to a high logic level. This situation affects both inputs as well as outputs that are three-stated. Use a 25-KΩ or lower pull-down resistor to bring a pin to a low level if needed.