Cypress CY7C638xx, CY7C63310 manual Introduction, Conventions

CY7C63310, CY7C638xx

3. Introduction

Cypress has reinvented its leadership position in the low speed USB market with a new family of innovative microcontrollers. Introducing enCoRe II USB - “enhanced Component Reduction.” Cypress has leveraged its design expertise in USB solutions to advance its family of low speed USB microcontrollers, which enable peripheral developers to design new products with a minimum number of components. The enCoRe II USB technology builds on the enCoRe family. The enCoRe family has an integrated oscillator that eliminates the external crystal or resonator, reducing overall cost. Also integrated into this chip are other external components commonly found in low speed USB applications, such as pull up resistors, wakeup circuitry, and a 3.3V regulator. Integrating these components reduces the overall system cost.

The enCoRe II is an 8-bit Flash programmable microcontroller with an integrated low speed USB interface. The instruction set is optimized specifically for USB and PS/2 operations, although the microcontrollers may be used for a variety of other embedded applications.

The enCoRe II features up to 20 GPIO pins to support USB, PS/2, and other applications. The IO pins are grouped into four ports (Port 0 to 3). The pins on Port 0 and Port 1 may each be configured individually while the pins on Ports 2 and 3 are configured only as a group. Each GPIO port supports high impedance inputs, configurable pull up, open drain output, CMOS/TTL inputs, and CMOS output with up to five pins that support a programmable drive strength of up to 50 mA sink current. GPIO Port 1 features four pins that interface at a voltage level of 3.3V. Additionally, each IO pin may be used to generate a GPIO interrupt to the microcontroller. Each GPIO port has its own GPIO interrupt vector; in addition, GPIO Port 0 has three dedicated pins that have independent interrupt vectors (P0.2 - P0.4).

The enCoRe II features an internal oscillator. With the presence of USB traffic, the internal oscillator may be set to precisely tune to USB timing requirements (24 MHz ±1.5%). Optionally, an external 12 MHz or 24 MHz clock is used to provide a higher precision reference for USB operation. The clock generator provides the 12 MHz and 24 MHz clocks that remain internal to the microcontroller. The enCoRe II also has a 12-bit program- mable interval timer and a 16-bit Free Running Timer with Capture Timer registers. In addition, the enCoRe II includes a Watchdog timer and a vectored interrupt controller.

The enCoRe II has up to eight Kbytes of Flash for user code and up to 256 bytes of RAM for stack space and user variables.

The power on reset circuit detects logic when power is applied to the device, resets the logic to a known state, and begins executing instructions at Flash address 0x0000. When power falls below a programmable trip voltage, it generates a reset or may be configured to generate an interrupt. There is a low voltage detect circuit that detects when VCC drops below a programmable trip voltage. It is configurable to generate an LVD interrupt to inform the processor about the low voltage event. POR and LVD share the same interrupt. There is no separate interrupt for each. The Watchdog timer may be used to ensure the firmware never gets stalled in an infinite loop.

The microcontroller supports 22 maskable interrupts in the vectored interrupt controller. Interrupt sources include a USB bus reset, LVR/POR, a programmable interval timer, a 1.024 ms output from the free-running timer, three USB endpoints, two capture timers, four GPIO Ports, three Port 0 pins, two SPI, a 16-bit free running timer wrap, an internal sleep timer, and a bus active interrupt. The sleep timer causes periodic interrupts when enabled. The USB endpoints interrupt after a USB transaction complete is on the bus. The capture timers interrupt when a new timer value is saved because of a selected GPIO edge event. A total of seven GPIO interrupts support both TTL or CMOS thresholds. For additional flexibility on the edge sensitive GPIO pins, the interrupt polarity is programmed as rising or falling.

The free-running 16-bit timer provides two interrupt sources: the 1.024 ms outputs and the free running counter wrap interrupt. The programmable interval timer provides up to 1 μsec resolution and provides an interrupt every time it expires. These timers are used to measure the duration of an event under firmware control by reading the desired timer at the start and at the end of an event, then calculating the difference between the two values. The two 8-bit capture timer registers save a programmable 8-bit range of the free-running timer when a GPIO edge occurs on the two capture pins (P0.5, P0.6). The two 8-bit captures may be ganged into a single 16-bit capture.

The enCoRe II includes an integrated USB serial interface engine (SIE) that allows the chip to easily interface to a USB host. The hardware supports one USB device address with three endpoints.

The USB D+ and D– pins are optionally used as PS/2 SCLK and SDATA signals so that products are designed to respond to either USB or PS/2 modes of operation. The PS/2 operation is supported with internal 5 KΩ pull up resistors on P1.0 (D+) and P1.1 (D–), and an interrupt to signal the start of PS/2 activity. In USB mode, the integrated 1.5 KΩ pull up resistor on D– may be controlled under firmware. No external components are necessary for dual USB and PS/2 systems, and no GPIO pins need to be dedicated to switching between modes.

The enCoRe II supports in system programming by using the D+ and D– pins as the serial programming mode interface. The programming protocol is not USB.

4. Conventions

In this data sheet, bit positions in the registers are shaded to indicate which members of the enCoRe II family implement the bits.

Available in all enCoRe II family members

CY7C638(1/2/3)3 only

Document 38-08035 Rev. *K Page 3 of 83

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