CYPD1120
The I2C peripheral is compatible with the I2C Standard-mode,
Fast-mode, and Fast-mode Plus devices, as defined in the NXP
I2C-bus specification and user manual (UM10204). The I2C bus
I/O is implemented with GPIO in open-drain modes.
The CCG1 is not completely compliant with the I2C spec in the
following respects:
Functional Definition
CPU and Memory Subsystem
CPU
The Cortex-M0 CPU in the CCG1 is part of the 32-bit MCU
subsystem, which is optimized for low-power operation with
extensive clock gating. It mostly uses 16-bit instructions and
executes a subset of the Thumb-2 instruction set. This enables
fully compatible binary upward migration of the code to higher
performance processors such as the Cortex-M3 and M4, thus
enabling upward compatibility. The Cypress implementation
includes a hardware multiplier that provides a 32-bit result in one
cycle. It includes a nested vectored interrupt controller (NVIC)
block with 32 interrupt inputs and a Wakeup Interrupt Controller
(WIC). The WIC can wake the processor up from the Deep Sleep
mode, allowing power to be switched off to the main processor
when the chip is in the Deep Sleep mode. The Cortex-M0 CPU
provides a Non-Maskable Interrupt (NMI) input, which is made
available to the user when it is not in use for system functions
requested by the user.
■ GPIO cells are not overvoltage tolerant and, therefore, cannot
be hot-swapped or powered up independently of the rest of the
I2C system.
■ Fast-mode Plus has an IOL specification of 20 mA at a VOL of
0.4 V. The GPIO cells can sink a maximum of 8 mA IOL with a
VOL maximum of 0.6 V.
■ Fast-mode and Fast-mode Plus specify minimum Fall times,
which are not met with the GPIO cell; Slow strong mode can
help meet this spec depending on the Bus Load.
■ When the SCB is an I2C Master, it interposes an IDLE state
between NACK and Repeated Start; the I2C spec defines Bus
free as following a Stop condition so other Active Masters do
not intervene but a Master that has just become activated may
start an Arbitration cycle.
The CPU also includes a debug interface, the serial wire debug
(SWD) interface, which is a 2-wire form of JTAG; the debug
configuration used for CCG1 has four break-point (address)
comparators and two watchpoint (data) comparators.
■ When the SCB is in the I2C Slave mode, and Address Match
on External Clock is enabled (EC_AM = 1) along with operation
in the internally clocked mode (EC_OP = 0), then its I2C
address must be even.
Flash
The CCG1 device has a flash module with a flash accelerator,
tightly coupled to the CPU to improve average access times from
the flash block. The flash block is designed to deliver 1 wait-state
(WS) access time at 48 MHz and 0-WS access time at 24 MHz.
The flash accelerator delivers 85% of single-cycle SRAM access
performance on average. Part of the flash module can be used
to emulate EEPROM operation if required.
GPIO
The CCG1 has up to 10 GPIOs, which are configured for various
functions. Refer to the pinout tables for the definitions. The GPIO
block implements the following:
■ Eight drive strength modes:
❐ Analog input mode (input and output buffers disabled)
❐ Input only
SROM
❐ Weak pull-up with strong pull-down
❐ Strong pull-up with weak pull-down
❐ Open drain with strong pull-down
❐ Open drain with strong pull-up
❐ Strong pull-up with strong pull-down
❐ Weak pull-up with weak pull-down
A supervisory ROM that contains boot and configuration routines
is provided.
System Resources
Power System
The power system is described in detail in the section Power on
page 7. It provides assurance that voltage levels are as required
for each respective mode and either delay mode entry (on
power-on reset (POR), for example) until voltage levels are as
required for proper function or generate resets (Brown-Out
Detect (BOD)) or interrupts (Low Voltage Detect (LVD)). The
CCG1 operates with a single external supply over the range of
1.8 to 5.5 V and has three different power modes: Active, Sleep,
and Deep Sleep; transitions between modes are managed by the
power system.
■ Input threshold select (CMOS or LVTTL).
■ Individual control of input and output buffer enabling/disabling
in addition to the drive strength modes.
■ Hold mode for latching previous state (used for retaining I/O
state in Deep Sleep mode).
■ Selectable slew rates for dV/dt related noise control to improve
EMI.
During power-on and reset, the I/O pins are forced to the disable
state so as not to crowbar any inputs and/or cause excess
turn-on current. A multiplexing network, known as a high-speed
I/O matrix, is used to multiplex between various signals that may
connect to an I/O pin.
Serial Communication Blocks (SCB)
The CCG1 has one SCB, which can implement an I2C interface.
The hardware I2C block implements a full multi-master and slave
interface (it is capable of multimaster arbitration). In addition, the
block supports an 8-deep FIFO for receive and transmit which,
by increasing the time given for the CPU to read data, greatly
reduces the need for clock stretching caused by the CPU not
having read data on time.
Document Number: 001-96786 Rev. *C
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