®
PSoC Creator™ Component Datasheet
EZI2C Slave
1.90
Features
Industry standard NXP® I2C bus interface
Emulates common I2C EEPROM interface
Only two pins (SDA and SCL) required to interface to I2C bus
Standard data rates of 50/100/400/1000 kbps
High level APIs require minimal user programming
Supports one or two address decoding with independent memory buffers
Memory buffers provide configurable Read/Write and Read Only regions
General Description
The EZI2C Slave component implements an I2C register-based slave device. It is compatible [1]
with I2C Standard-mode, Fast-mode, and Fast-mode Plus devices as defined in the NXP I2C-bus
specification. The master initiates all communication on the I2C bus and supplies the clock for all
slave devices. The EZI2C Slave supports standard data rates up to 1000 kbps and is compatible
with multiple devices on the same bus.
The EZI2C Slave is a unique implementation of an I2C slave in that all communication between
the master and slave is handled in the ISR (Interrupt Service Routine) and requires no
interaction with the main program flow. The interface appears as shared memory between the
master and slave. Once the EZI2C_Start() function is executed, there is little need to interact
with the API.
1
2
2
The I C peripheral is non-compliant with the NXP I C specification in the following areas: analog glitch filter, I/O
2
VOL/IOL, I/O hysteresis. The I C Block has a digital glitch filter (not available in sleep mode). The Fast-mode
minimum fall-time specification can be met by setting the I/Os to slow speed mode. See the I/O Electrical
Specifications in "Inputs and Outputs" section of device datasheet for details.
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 001-88525 Rev. *B
Revised December 11, 2014
EZI2C Slave
®
PSoC Creator™ Component Datasheet
When to Use an EZI2C Slave
Use this component when you want a shared memory model between the I2C Slave and I2C
Master. You may define the EZI2C Slave buffers as any variable, array, or structure in your code
without worrying about the I2C protocol. The I2C master may view any of the variables in this
buffer and modify the variables defined by the EZI2C_SetBuffer1() or EZI2C_SetBuffer2()
functions.
Input/Output Connections
This section describes the various input and output connections for EZI2C Slave.
sda – In/Out
Serial data (SDA) is the I2C data signal. It is a bidirectional data signal used to transmit or
receive all bus data.
scl – In/Out
Serial clock (SCL) is the master generated I2C clock. Although the slave never generates the
clock signal, it may hold it low stalling the bus until it is ready to send data or NAK/ACK the latest
data or address.
Schematic Macro Information
The default EZI2C Slave in the Component Catalog is a schematic macro using an EZI2C Slave
component with default settings. The EZI2C Slave component is connected to a Pins
component, which is configured as an SIO pair.
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PSoC Creator™ Component Datasheet
EZI2C Slave
Component Parameters
Drag an EZI2C component onto your design and double-click it to open the Configure dialog.
The EZI2C component provides the following parameters.
Data rate
This parameter is used to set the I2C data rate value up to 1000 kbps; the actual rate may differ,
based on available clock speed and divider range. The standard data rates are 50, 100 (default),
400, and 1000 kbps.
Number of addresses
This option determines whether 1 (default) or 2 independent I2C slave addresses are recognized.
If two addresses are recognized, address detection will be performed in software, not hardware;
therefore, the Enable wakeup from Sleep Mode option is not available.
Primary slave address
This is the primary I2C slave address (default is 8). This value can be entered in decimal or
hexadecimal format. For hexadecimal, type ‘0x’ before the number. This address is the 7-bit
right-justified slave address and does not include the R/W bit.
Secondary slave address
This is the secondary I2C slave address (default is 9). This value can be entered in decimal and
hexadecimal format. For hexadecimal, type ‘0x’ before the number. This second address is only
valid when the Number of addresses parameter is set to 2. The primary and secondary slave
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EZI2C Slave
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PSoC Creator™ Component Datasheet
addresses must be different. This address is the 7-bit right-justified slave address and does not
include the R/W bit.
Sub-address Size
This option determines what range of data can be accessed. You can select a sub-address of 8
bits (default) or 16 bits. If you use an address size of 8 bits, the master can only access data
offsets between 0 and 255. You may also select a sub-address size of 16 bits. That will allow the
I2C master to access data arrays of up to 65,536 bytes at each slave address.
Pin connections
This parameter determines which type of pin to use for SDA and SCL signal connections. This
option is supplemental for the Enable wakeup from Sleep Mode option and is available only if
single I2C address is selected in the Number of addresses option. There are three possible
values: Any, I2C0, and I2C1. The default is Any.
Any means general-purpose I/O (GPIO).
If Enable wakeup from Sleep Mode is not required, Any should be used for SDA and
SCL.
If you need Enable wakeup from Sleep Mode, you must use the pairs of pins I2C0
(P12[4], P12[5]) or I2C1 (P12[0], P12[1]), which allows you to configure the device for
wakeup on I2C address match.
Enable wakeup from Sleep Mode
This parameter allows the device to be awakened from sleep mode on slave address match.
This option is disabled by default. The wake up on address match option is valid if a single I2C
address is selected and the SDA, and SCL signals are connected to SIO ports (pin pairs I2C0 or
I2C1). Enable wakeup from Sleep Mode will be supported in PSoC 3 and PSoC 5LP.
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PSoC Creator™ Component Datasheet
EZI2C Slave
Application Programming Interface
Application Programming Interface (API) routines allow you to configure the component using
software. The following table lists and describes the interface to each function. The subsequent
sections cover each function in more detail.
By default, PSoC Creator assigns the instance name “EZI2C_1” to the first instance of a
component in a given design. You can rename it to any unique value that follows the syntactic
rules for identifiers. The instance name becomes the prefix of every global function name,
variable, and constant symbol. For readability, the instance name used in the following table is
“EZI2C.”
Basic Functions
Function
Description
2
EZI2C_Start()
Starts responding to I C traffic. Enables interrupt.
EZI2C_Stop()
Stops responding to I C traffic. Disables interrupt.
EZI2C_EnableInt()
Enables interrupt, which is required for most I C operations.
EZI2C_DisableInt()
Disables interrupt. The EZI2C_Stop() API does this automatically.
EZI2C_SetAddress1()
Sets the primary I C address.
EZI2C_GetAddress1()
Returns the primary I C address.
EZI2C_SetBuffer1()
Sets the buffer pointer for the primary I C.
EZI2C_GetActivity()
Checks component activity status.
EZI2C_Sleep()
Stops I C operation and saves I C configuration. Disables interrupt.
EZI2C_Wakeup()
Restores I C configuration and starts I C operation. Enables interrupt.
EZI2C_Init()
Initializes I C registers with initial values provided from customizer.
EZI2C_Enable()
Activates the hardware and begins component operation.
EZI2C_SaveConfig()
Saves the current user configuration of the EZI2C component.
EZI2C_RestoreConfig()
Restores nonretention I C registers.
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2
2
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PSoC Creator™ Component Datasheet
void EZI2C_Start(void)
Description:
This is the preferred method to begin component operation. EZI2C_Start() sets the initVar
variable, calls the EZI2C_Init() function, and then calls the EZI2C_Enable() function. It must
2
be executed before I C bus operation.
After EZI2C_Start() calls EZI2C_Enable(), EZI2C_Enable() calls the EZI2C_EnableInt(),
2
which enables the I C interrupt.
Parameters:
None
Return Value:
None
Side Effects:
None
void EZI2C_Stop(void)
2
2
Description:
Disables I C hardware and disables I C interrupt. Disables Active mode power template bits
or clock gating as appropriate.
Parameters:
None
Return Value:
None
Side Effects:
None
void EZI2C_EnableInt(void)
2
Description:
Enables I C interrupt. Interrupts are required for most operations. Called when calling the
EZI2C_Start() API.
Parameters:
None
Return Value:
None
Side Effects:
None
void EZI2C_DisableInt(void)
2
Description:
Disables I C interrupts. This function is not normally required because the Stop function
disables the interrupt.
Parameters:
None
Return Value:
None
Side Effects:
If the I C interrupt is disabled while the I C is still running, the I C bus may lock up.
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PSoC Creator™ Component Datasheet
EZI2C Slave
void EZI2C_SetAddress1(uint8 address)
2
Description:
This function sets the I C address for the primary memory buffer. This value can be any
value between 0 and 127.
Parameters:
address: The 7-bit slave address between 0 and 127. The address is right justified and does
not include the R/W bit.
Return Value:
None
Side Effects:
None
uint8 EZI2C_GetAddress1(void)
2
Description:
Returns the I C slave address for the primary memory buffer.
Parameters:
None
Return Value:
The same I C slave address set by SetAddress1 or the default I C address.
Side Effects:
None
2
2
void EZI2C_SetBuffer1(uint16 bufSize, uint16 rwBoundry, volatile uint8 * dataPtr)
Description:
This function sets the buffer pointer, size, and read/write area for the slave data. This is the
2
data that is exposed to the I C Master.
Parameters:
bufSize: Size of the buffer in bytes.
rwBoundry: Sets how many bytes are writable in the beginning of the buffer. This value
must be less than or equal to the buffer size. Data located at offset rwBoundry and greater
are read only.
dataPtr: Pointer to the data buffer.
Return Value:
None
Side Effects:
The EZI2C_Start() must be called before this function.
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PSoC Creator™ Component Datasheet
uint8 EZI2C_GetActivity(void)
Description:
2
This function returns a nonzero value if an I C read or write cycle has occurred since the last
time this function was called. The activity flag resets to zero at the end of this function call.
The Read and Write busy flags are cleared when read, but the “BUSY” flag is only cleared by
2
an I C Stop.
Parameters:
A nonzero value is returned if activity is detected.
Return Value: Status of I2C activity.
Constant
Side Effects:
Description
EZI2C_STATUS_READ1
Set if Read sequence is detected for first address. Cleared
when status is read.
EZI2C_STATUS_WRITE1
Set if Write sequence is detected for first address. Cleared
when status is read.
EZI2C_STATUS_READ2
Set if Read sequence is detected for second address (if
enabled). Cleared when status is read.
EZI2C_STATUS_WRITE2
Set if Write sequence is detected for second address (if
enabled). Cleared when status is read.
EZI2C_STATUS_BUSY
Set if Start is detected. Cleared when stop is detected.
EZI2C_STATUS_ERR
Set when I C hardware error is detected. Cleared when
status is read.
2
None
void EZI2C_Sleep(void)
Description:
This is the preferred API to prepare the component for sleep if Enable wakeup from Sleep
Mode is not selected. The EZI2C_Sleep() API saves the current component state. Then it
calls the EZI2C_Stop() function and calls EZI2C_SaveConfig() to save the hardware
configuration.
Call the EZI2C_Sleep() function before calling the CyPmSleep() or the CyPmHibernate()
function. Refer to the PSoC Creator System Reference Guide for more information about
power-management functions.
Parameters:
None
Return Value:
None
Side Effects:
None
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PSoC Creator™ Component Datasheet
EZI2C Slave
void EZI2C_Wakeup(void)
Description:
This is the preferred API to restore the component to the state when EZI2C_Sleep() was
called. The EZI2C_Wakeup() function calls the EZI2C_RestoreConfig() function to restore
the hardware configuration. If the component was enabled before the EZI2C_Sleep()
function was called, the EZI2C_Wakeup() function will also re-enable the component.
Parameters:
None
Return Value:
None
Side Effects:
Calling this function before EZI2C_SaveConfig() or EZI2C_Sleep() may produce
unexpected behavior.
void EZI2C_Init(void)
Description:
Initializes or restores the component according to the Configure dialog settings. It is not
necessary to call EZI2C_Init() because the EZI2C_Start() API calls this function, which is
the preferred method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
All registers will be set to values according to the Configure dialog
void EZI2C_Enable(void)
Description:
Activates the hardware and begins component operation. It is not necessary to call
EZI2C_Enable() because the EZI2C_Start() API calls this function, which is the preferred
2
method to begin component operation. Calls EZI2C_EnableInt() to enable the I C interrupt.
Parameters:
None
Return Value:
None
Side Effects:
None
void EZI2C_SaveConfig(void)
Description:
This function saves the component configuration and nonretention registers. It also saves
the current component parameter values, as defined in the Configure dialog or as modified
by appropriate APIs. This function is called by the EZI2C_Sleep() function.
Parameters:
None
Return Value:
None
Side Effects:
None
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PSoC Creator™ Component Datasheet
void EZI2C_RestoreConfig(void)
Description:
This function restores the component configuration and nonretention registers. It also
restores the component parameter values to what they were prior to calling the
EZI2C_Sleep() function.
Parameters:
None
Return Value:
None
Side Effects:
Calling this function before EZI2C_Sleep() or EZI2C_SaveConfig() may produce
unexpected behavior.
Optional Second Address APIs
These commands are present only if two I2C addresses are enabled.
Function
Description
2
EZI2C_SetAddress2()
Sets the secondary I C address.
EZI2C_GetAddress2()
Returns the secondary I C address.
EZI2C_SetBuffer2()
Sets the buffer pointer for the secondary I C.
2
2
void EZI2C_SetAddress2(uint8 address)
2
Description:
Sets the I C slave address for the secondary memory buffer. This value may be any value
2
between 0 and 127. This function is only provided if two I C addresses have been selected
in the user parameters.
Parameters:
address: The 7-bit slave address between 0 and 127. The address is right justified and
does not include the R/W bit.
Return Value:
None
Side Effects:
None
uint8 EZI2C_GetAddress2(void)
2
Description:
Returns the I C slave address for the secondary memory buffer. This function is only
2
provided if two I C addresses have been selected in the user parameters.
Parameters:
None
Return Value:
The same I C slave address set by SetAddress2 or the default I C address.
Side Effects:
None
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PSoC Creator™ Component Datasheet
EZI2C Slave
void EZI2C_SetBuffer2(uint16 bufSize, uint16 rwBoundry, volatile uint8 * dataPtr)
Description:
This function sets the buffer pointer, size, and read/write area for the second slave data.
2
2
This is the data that is exposed to the I C Master for the second I C address. This function
2
is only provided if two I C addresses have been selected in the user parameters.
Parameters:
bufSize: Size of the buffer exposed to the I C master.
2
2
rwBoundry: Sets how many bytes are readable and writable by the I C master. This value
must be less than or equal to the buffer size. Data located at offset rwBoundry and greater
are read only.
2
dataPtr: This is a pointer to the data array or structure that is used for the I C data buffer.
Return Value:
None
Side Effects:
The EZI2C_Start() must be called before this function.
Global Variables
Knowledge of these variables is not required for normal operations.
Function
EZI2C_initVar
Description
Indicates whether the EZI2C has been initialized. The variable is initialized to 0 and set to
1 the first time EZI2C_Start() is called. This allows the component to restart without
reinitialization after the first call to the EZI2C_Start() routine.
If reinitialization of the component is required the variable should be set to 0 before the
EZI2C_Start() routine is called. Alternatively, the EZI2C can be reinitialized by calling the
EZI2C_Init() and EZI2C_Enable() functions.
2
EZI2C_dataPtrS1
Stores pointer to the data exposed to an I C master for the first slave address.
EZI2C_rwOffsetS1
Stores offset for read and write operations. It is set at each write sequence of the first
slave address.
EZI2C_rwIndexS1
Stores pointer to the next value to be read or written for the first slave address.
EZI2C_wrProtectS1
Stores offset where data is read only for the first slave address.
EZI2C_bufSizeS1
Stores size of data array exposed to an I C master for the first slave address.
EZI2C_dataPtrS2
Stores pointer to the data exposed to an I C master for the second slave address.
EZI2C_rwOffsetS2
Stores offset for read and write operations, is set at each write sequence of the second
slave device.
EZI2C_rwIndexS2
Stores pointer to the next value to be read or written for the second slave address.
EZI2C_wrProtectS2
Stores offset where data is read only for the second slave address.
EZI2C_bufSizeS2
Stores size of data array exposed to an I C master for the second slave address.
EZI2C_curState
Stores current state of an I C state machine.
EZI2C_curStatus
Stores current status of the component.
2
2
2
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PSoC Creator™ Component Datasheet
Sample Firmware Source Code
PSoC Creator provides numerous example projects that include schematics and example code
in the Find Example Project dialog. For component-specific examples, open the dialog from the
Component Catalog or an instance of the component in a schematic. For general examples,
open the dialog from the Start Page or File menu. As needed, use the Filter Options in the
dialog to narrow the list of projects available to select.
Refer to the “Find Example Project” topic in the PSoC Creator Help for more information.
MISRA Compliance
This section describes the MISRA-C:2004 compliance and deviations for the component. There
are two types of deviations defined:
project deviations – deviations that are applicable for all PSoC Creator components
specific deviations – deviations that are applicable only for this component
This section provides information on component-specific deviations. Project deviations are
described in the MISRA Compliance section of the System Reference Guide along with
information on the MISRA compliance verification environment.
The EZI2C component has the following specific deviations:
Rule
Class
[2]
Rule Description
Description of Deviation(s)
17.4
R
Array indexing shall be the only
allowed form of pointer arithmetic.
Component uses array indexing operation to access
buffers. The buffer size is checked before access. It is
safe operation unless user provides incorrect buffer size.
19.7
A
A function should be used in
Deviated since function-like macros are used to allow
preference to a function-like macro. more efficient code.
This component has the following embedded component: Interrupt. Refer to the corresponding
component datasheet for information on their MISRA compliance and specific deviations.
API Memory Usage
The component memory usage varies significantly, depending on the compiler, device, number
of APIs used and component configuration. The following table provides the memory usage for
all APIs available in the given component configuration.
2
Required / Advisory
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PSoC Creator™ Component Datasheet
EZI2C Slave
The measurements have been done with associated compiler configured in Release mode with
optimization set for Size. For a specific design the map file generated by the compiler can be
analyzed to determine the memory usage.
PSoC 3 (Keil_PK51)
Configuration
PSoC 5LP (GCC)
Flash
SRAM
Flash
SRAM
Bytes
Bytes
Bytes
Bytes
One address
1265
21
1412
25
Two addresses
1751
37
1644
43
Functional Description
This component supports an I2C slave device with one or two I2C addresses. Either address may
access a memory buffer defined in RAM, EEPROM, or flash data space. EEPROM and flash
memory buffers are read only, while RAM buffers may be read/write. The addresses are right
justified.
When using this component, you must enable global interrupts because the I2C hardware is
interrupt driven. Even though this component requires interrupts, you do not need to add any
code to the ISR (Interrupt Service Routine). The module services all interrupts (data transfers)
independent of your code. The memory buffers allocated for this interface look like simple dualport memory between your application and the I2C Master.
If required, you can create a higher-level interface between a master and slave by defining
semaphores and command locations in the data structure.
Memory Interface
To an I2C master, the interface looks very similar to a common I2C EEPROM. The EZI2C
interface can be configured as simple variables, arrays, or structures but the safer method is
using arrays. In a sense it acts as one or two shared memory interfaces between your program
and an I2C master through the I2C bus. The component only allows the I2C master to access the
specified area of memory and prevents any reads or writes outside that area. For example, if the
buffer for the primary slave address is configured as shown in the following code example, the
buffer representation in memory could be represented as shown in Figure 1.
#define BUFFER_SIZE
#define BUFFER_RW_AREA_SIZE
(0x0Au)
(0x04u)
uint8 ezi2cBuffer[BUFFER_SIZE];
EZI2C_SetBuffer1(BUFFER_SIZE, BUFFER_RW_AREA_SIZE, ezi2cBuffer);
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PSoC Creator™ Component Datasheet
Figure 1. Memory Representation of the EZI2C Buffer Exposed to an I2C Master
RAM
0x00FF
Access type
Exposed Buffer
ezi2cBuffer[9]
ezi2cBuffer[8]
Read Only
ezi2cBuffer[7]
0x0016
ezi2cBuffer[6]
ezi2cBuffer[5]
ezi2cBuffer[4]
ezi2cBuffer[3]
Read/Write
ezi2cBuffer[2]
0x000D
ezi2cBuffer[1]
ezi2cBuffer[0]
0x0000
To make whole buffer with read and write access the buffer size and read/write boundary need
to be the same size. For example:
EZI2C_SetBuffer1(BUFFER_SIZE, BUFFER_SIZE, ezi2cBuffer);
Handle structures
The EZI2C buffer can be set up as structure. The interface (I2C Master) only sees the structure
as an array of bytes, and cannot access any memory outside the defined area.
The compiler lays out structures in the memory and may add extra bytes. This is called byte
padding. The compiler will add these bytes to align the fields of the structure to match the
requirements of the Cortex-M3. When using a structure, the application must take this alignment
into account. To avoid padding bytes the attribute “packed” should be used:
struct
{
uint8 status;
uint8 data0;
uint32 data1;
} __attribute__ ((packed)) ezi2cBuffer;
SCB_EzI2CSetBuffer1(sizeof(ezi2cBuffer), sizeof(ezi2cBuffer),(uint8 *)
&ezi2cBuffer);
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EZI2C Slave
Handling endianess
The data is transmitted in different endianess for different architectures. Therefore, extra code
must be put to send in a specific endianess. For example, the CY_GET_REGXX()/
CY_SET_REGXX() macros (XX stands for 16/24/32) can be used to match little-endian ordering
regardless of device architecture. For more information about endianess, see the Register
Access section of the System Reference Guide.
The following simple example shows only a single integer (two bytes) is exposed. Both bytes are
readable and writable by the I2C master.
uint16 ezi2cVariable1;
CY_SET_REG16(&ezi2cVariable1, 0xABCD);
EZI2C_SetBuffer1(2u, 2u, (uint8 *) (&ezi2cVariable1));
Interface as Seen by External Master
The EZI2C Slave component supports basic read and write operations for the read/write area
and read-only operations for the read-only area. The two I2C address interfaces contain separate
data buffers that are addressed with separate offset data pointers. The offset data pointers are
written by the master as the first one or two data bytes of a write operation, depending on the
Sub-address size parameter. The sub-address size of 8-bits is used to access buffers up to 256
bytes and sub-address size of 16-bits is used for buffers up to 65536 bytes. For the rest of this
discussion, we will concentrate on an 8-bit sub-address size.
Figure 2. The 8-bit and 16-bit Sub-Address Size (from top to bottom)
LSB
MSB
OFFSET DATA PTR
MSB
LSB MSB
LSB
OFFSET DATA PTR
For write operations, the first data byte is always the offset data pointer (two bytes for subaddress size = 16). The byte after the offset data pointer is written into the location pointed to by
the offset data pointer. The second data byte is written to the offset data pointer plus one, and so
on, until the write is complete. The length of a write operation is only limited by the maximum
buffer read/write region size. For write operations, the offset data pointer must always be
provided.
Read operations always begin at the offset data pointer provided by the most recent write
operation. The offset data pointer increments for each byte read, the same way as a write
operation. A new read operation will not continue from where the last read operation stopped. A
new read operation always begins to read data at the location pointed to by the last write
operation offset data pointer. The length of a read operation is only limited by the maximum size
of the data buffer.
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PSoC Creator™ Component Datasheet
Typically, a read will contain a write operation of only the offset data pointer followed by a restart
(or stop/start) and then the read operation. If the offset data pointer does not require update, as
in the case of repeatedly reading the same data, no additional write operations are required after
the first. This greatly speeds read operations by allowing them to directly follow each other.
Figure 3. Write x Bytes to I2C Slave
S SLAVE ADDR R/W A
DATA PTR
A
DATA[n]
from slave to master
A
DATA[n+1]
A
DATA[n+x]
A
P
A = acknowledge (SDA LOW)
A = not acknowledge (SDA HIGH)
S = START condition
from master to slave
P = STOP condition
For example, if the offset data pointer is set to four, a read operation begins to read data at
location four and continues sequentially until the data ends or the host completes the read
operation. This is true whether single or multiple read operations are performed. The offset data
pointer is not changed until a new write operation is initiated.
If the I2C master tries to write data past the area specified by the EZI2C_SetBuffer1() or
EZI2C_SetBuffer2() functions, the data is discarded and does not affect any RAM inside or
outside the designated RAM area. Data cannot be read outside the allowed range. Any read
requests by the master outside the allowed range results in the return of invalid data.
Figure 4 illustrates the data pointer write for an 8-bit offset data pointer.
Figure 4. Set Slave Data Pointer
S
SLAVE ADDR
R/
W
A
DATA PTR
A P
Figure 5 illustrates the read operation for an 8-bit offset data pointer. Remember that a data write
operation always rewrites the offset data pointer.
Figure 5. Read x Bytes from I2C Slave
S
SLAVE ADDR
R/
W
A
DATA[n]
A
DATA[n+1]
A
DATA[x]
A P
At reset, or power on, the EZI2C Slave component is configured and APIs are supplied, but the
resource must be explicitly turned on using the EZI2C_Start() function.
Detailed descriptions of the I2C bus and the implementation are available in the complete I2C
specification available on the Philips website, and by referring to the device datasheet.
Page 16 of 23
Document Number: 001-88525 Rev. *B
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PSoC Creator™ Component Datasheet
EZI2C Slave
Data Coherency
Although a data buffer may include a data structure larger than a single byte, a Master read or
write operation consists of multiple single-byte operations. This can cause a data coherency
problem, because there is no mechanism to guarantee that a multi-byte read or write will be
synchronized on both sides of the interface (Master and Slave). For example, consider a buffer
that contains a single two-byte integer. While the master is reading the two-byte integer one byte
at a time, the slave may have updated the entire integer between the time the master read the
first byte of the integer (LSB) and was about to read the second byte (MSB). The data read by
the master may be invalid, since the LSB was read from the original data and the MSB was read
from the updated value.
You must provide a mechanism on the master, slave, or both that guarantees that updates from
the master or slave do not occur while the other side is reading or writing the data. The
EZI2C_GetActivity() function can be used to develop an application-specific mechanism.
Wakeup from Sleep Mode
If you want to use the Enable wake up from Sleep Modefeature, you may need to design the
I2C Master to handle clock stretching procedure (hold SCL low).
The device clock’s configuration (bus clock frequency) can be modified (by the
CyPmSaveClocks() function) as part of the Sleep mode entry procedure. It must be restored (by
the CyPmRestoreClocks() function) before the I2C transaction can continue in Active mode.
To meet these requirements, the EZI2C interrupt remains enabled but interrupt handler is
changed before going to sleep in EZI2C_Sleep(). Wakeup on address match triggers EZI2C
interrupt and EZI2C wakeup flag is set to notify that. Call EZI2C_Wakeup() function changes
interrupt handler to regular EZI2C and generates interrupt based on EZI2C wakeup flag to
process in-coming transaction. The SCL line remains low after wakeup until EZI2C_Wakeup() is
called.
The following is the correct Sleep mode entry procedure if Enable wake up from Sleep Mode is
enabled:
/* Prepares EZI2C to wake up from Sleep mode */
EZI2C_Sleep();
/* Switches to the Sleep mode */
CyPmSaveClocks();
CyPmSleep(PM_SLEEP_TIME_NONE, PM_SLEEP_SRC_I2C);
CyPmRestoreClocks();
/* Prepares EZI2C to work in Active mode */
EZI2C_Wakeup();
Document Number: 001-88525 Rev. *B
Page 17 of 23
®
EZI2C Slave
PSoC Creator™ Component Datasheet
External Electrical Connections
As Figure 6 illustrates, the I2C bus requires external pull-up resistors. The pull-up resistors (RP)
are determined by the supply voltage, clock speed, and bus capacitance. Make the minimum
sink current for any device (master or slave) no less than 3 mA at VOLmax = 0.4 V for the output
stage. This limits the minimum pull-up resistor value for a 5-V system to about 1.5 kΩ. The
maximum value for RP depends upon the bus capacitance and clock speed. For a 5-V system
with a bus capacitance of 150 pF, the pull-up resistors should be no larger than 6 kΩ. For more
information see The I2C-Bus Specification on the Philips web site at www.philips.com.
Figure 6. Connection of Devices to the I2C-Bus
+VDD
pull-up
resistors
Rp
Rp
SDA (Serial Data Line)
SCL (Serial Clock Line)
Device 1
Device 2
Note Purchase of I2C components from Cypress or one of its sublicensed Associated
Companies, conveys a license under the Philips I2C Patent Rights to use these components in
an I2C system, provided that the system conforms to the I2C Standard Specification as defined
by Philips.
Clock Selection
The clock is tied to the system bus clock and cannot be changed by the user.
Interrupt Service Routine
The interrupt service routine is used by the component code. Do not change it.
Resources
The fixed-function I2C block and one interrupt are used for this component.
Page 18 of 23
Document Number: 001-88525 Rev. *B
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PSoC Creator™ Component Datasheet
EZI2C Slave
DC and AC Electrical Characteristics
Specifications are valid for –40 °C ≤ TA ≤ 85 °C and TJ ≤ 100 °C, except where noted.
Specifications are valid for 1.71 V to 5.5 V, except where noted.
DC Specifications
Parameter
IDD
Description
Block current consumption
Conditions
Min
Typ
Max
Units
Enabled, configured for 100 kbps
–
–
250
μA
Enabled, configured for 400 kbps
–
–
260
μA
Wake from sleep mode
–
–
30
μA
Min
Typ
Max
Units
–
–
1
Mbps
AC Specifications
Parameter
Description
Conditions
Bit rate
Component Errata
This section lists known problems with the component.
Cypress
ID
Component
Version
197653
v1.90
Problem
Within the Stop() API, the I2C fixed-function
block is reset. This action requires reloading the
address register value. For reliable operation of
the address loading, the Stop() API needs check
that the I2C fixed function block accepts the
address value.
Workaround
Add a routine to confirm that the
proper address register value is
restored. This guarantees the
component to work with any Bus
Clock frequency in the design.
Refer to the recommendation below.
Find the Stop() function in the EZI2C.c file located at:
for 64-bit operating system – c:\Program Files (x86)\Cypress\PSoC Creator\3.1\PSoC
Creator\psoc\content\CyComponentLibrary\CyComponentLibrary.cylib\EZI2C_v1_90\API\
for 32-bit operating system – c:\Program Files\Cypress\PSoC Creator\3.1\PSoC
Creator\psoc\content\CyComponentLibrary\CyComponentLibrary.cylib\EZI2C_v1_90\API\
Modify the Stop() function as follows:
1. Declare variable i
uint8 i;
Document Number: 001-88525 Rev. *B
Page 19 of 23
®
EZI2C Slave
PSoC Creator™ Component Datasheet
2. Add a routine to write and check the address register, until the value read back equals the
value written to.
/* Reset fixed-function block */
`$INSTANCE_NAME`_CFG_REG &= ((uint8) ~`$INSTANCE_NAME`_CFG_EN_SLAVE);
`$INSTANCE_NAME`_CFG_REG |= `$INSTANCE_NAME`_CFG_EN_SLAVE;
i = 255u;
do
{
`$INSTANCE_NAME`_ADDR_REG = `$INSTANCE_NAME`_backup.adr;
i--;
}
while ((`$INSTANCE_NAME`_ADDR_REG != `$INSTANCE_NAME`_backup.adr) &&
(i != 0u));
Component Changes
This section lists the major changes in the component from the previous version.
Version
Description of Changes
Reason for Changes / Impact
1.90.b
Datasheet updated to add Component Errata
section.
Refer to Cypress ID 197653.
1.90.a
Updated the datasheet only.
API sections were out of order. Also updated to
comply with latest template.
1.90
Updated MISRA Compliance section.
The component has specific deviations described.
The type of global variables EZI2C_bufSizeS1,
EZI2C_wrProtectS1, EZI2C_bufSizeS2 and
EZI2C_wrProtectS2 were changed from uint8 to
uint16.
The buffer length equal 256 bytes is supported if the
Sub-Address Size is 8 bits.
Removed mention about
EZI2C_SlaveSetSleepMode() and
EZI2C_SlaveSetWakeMode().
These are obsolete functions. EZI2C_Sleep() and
EZI2C_Wakeup() have to be used instead of it.
Added Handle structures section
Documentation enhancement
Added MISRA Compliance section.
The component was not verified for MISRA
compliance.
Added footnote about non-compliant with the
2
NXP I C specification in the some areas.
Documentation enhancement.
Changed the control flow of the wake up
2
sequence to avoid disabling the I C interrupt.
PSoC 5 LP requires an I C interrupt to be enabled
in order to wake up the device at the event of an
address match.
Fixed control flow behavior when master
completes reading beyond the buffer size.
The slave doesn’t complete transaction correctly
because NAK from master was not checked.
1.80
1.70.a
2
Corrected figure 5.
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Document Number: 001-88525 Rev. *B
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PSoC Creator™ Component Datasheet
Version
Description of Changes
EZI2C Slave
Reason for Changes / Impact
1.70
Added PSoC 5LP support.
1.61
Enhanced verification of the options configured
within the customizer and related to the Enable
wakeup from Sleep Mode option.
Prevents components from being configured with an
unsupported mode.
Updated EZI2C_Stop() implementation for
PSoC 3 devices.
Makes EZI2C_Stop() release the bus if it was
locked.
2
Updated the default I C addresses to 8 and 9 to
2
comply with I C bus specification requirements.
Previously used addresses are reserved according
2
to the I C bus specification.
Updated the component debugger tool window
support.
Enhanced debug window support.
Added the possibility to declare every function
as reentrant for PSoC 3 by adding the function
name to the .cyre file.
Not all APIs are truly reentrant. Comments in the
component API source files indicate which functions
cannot be truly reentrant.
This change is required to eliminate compiler
warnings for functions that are used in a safe way
(protected from concurrent calls by flags or Critical
Sections) and are not reentrant.
1.60.b
Datasheet corrections
1.60.a
Updated the Pin Connections section with
information about dependencies between the
Enable wakeup from Sleep mode and Number
of addresses options.
Explained that option is supplemental for the Enable
wakeup from Sleep mode option and is also
2
available only if a single I C address is selected in
Number of addresses option.
Figures 2, 3, and 5 were updated to show bit
fields.
Visibility enhancement,
Clarified the method of writing portable code
regardless of the PSoC device architecture.
Documentation enhancement.
The method of working with the slave enable bit
was changed: EZI2C_Stop() does not clear this
bit now and setting this bit was moved from
2
EZI2C_Enable() to EZI2C_Init(). The I C
configuration register is now restored in
EZI2C_RestoreConfig() function.
To achieve correct result of EZI2C_Start() EZI2C_Stop() - EZI2C_Start() and EZI2C_Sleep() EZI2C_Wakeup() sequences. No functional impact
is expected.
1.60
2
The label I2C Bus Speed: in the customizer was Consistency between I C-Bus Specification naming
2
replaced with Data Rate. The Wakeup from
and I C/EZI2C components.
Sleep Mode section was added to the
Functional Description.
The label "I2C pins connected to" in customizer
was replaced with "Pin Connections"
The text was fixed for consistency with
requirements.
The label "Enable wakeup from the Sleep
mode" in customizer was replaced with "Enable
wakeup from Sleep mode"
The text was fixed for consistency with
requirements.
Document Number: 001-88525 Rev. *B
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EZI2C Slave
Version
PSoC Creator™ Component Datasheet
Description of Changes
Reason for Changes / Impact
The component symbol and catalog placement
name was updated: the “EZ I2C” was renamed
to “EZI2C”.
The text was fixed for consistency with
requirements.
Fixed issues when global variables used in both
code and ISR could potentially be optimized out
by compiler.
Prevents optimization issues that could lead to
unexpected result.
Added characterization data to datasheet
Minor datasheet edits and updates
1.50.a
Moved component into subfolders of the
component catalog
1.50
Standard data rate has been updated to support Allows setting up I C bus speed up to 1 Mbps.
up to 1 Mbps.
2
Keil reentrancy support was added.
Support for PSoC 3 with the Keil compiler the
capability for functions to be called from multiple
flows of control.
Added Sleep/Wakeup and Init/Enable APIs.
To support low-power modes and to provide
common interfaces to separate control of
initialization and enabling of most components.
The XML description of the component has
been added.
This allows PSoC Creator to provide a mechanism
for creating new debugger tool windows for this
component.
Added support for the PSoC 3 Production
devices.
The required changes have been applied to support
hardware changes between PSoC 3 ES2 and
Production devices.
The default schematic template has been added Every component should have a schematic
to the component catalog.
template.
2
The EZI2C's bus speed generation was fixed.
Previously it was x4 greater than should be.
Added more comments in the source code to
describe bus speed calculation.
The proper I C bus speed calculation and
generation.
Optimized form height for Microsoft Windows 7.
In Windows 7 scrollbar appeared just after
customizer start.
Added tooltips for address input boxes with 'Use To inform user about possibility of hexadecimal
0x prefix for hexadecimals' text.
input.
1.20.a
Moved component into subfolders of the
component catalog.
Added information to the component that
advertizes its compatibility with silicon revisions.
1.20
The tool reports an error/warning if the component
is used on incompatible silicon. If this happens,
update to a revision that supports your target
device.
Updated the Configure dialog.
Page 22 of 23
Document Number: 001-88525 Rev. *B
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PSoC Creator™ Component Datasheet
Version
Description of Changes
EZI2C Slave
Reason for Changes / Impact
Changed Digital Port to Pins component in the
schematic
© Cypress Semiconductor Corporation, 2014. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of
any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used
for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for
use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in lifesupport systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
PSoC® is a registered trademark, and PSoC Creator and Programmable System-on-Chip are trademarks of Cypress Semiconductor Corp. All other trademarks or registered trademarks
referenced herein are property of the respective corporations.
Any Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide patent protection (United States and
foreign), United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a personal, non-exclusive, non-transferable license to copy, use, modify, create
derivative works of, and compile the Cypress Source Code and derivative works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in
conjunction with a Cypress integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source Code except as
specified above is prohibited without the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials described herein.
Cypress does not assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in lifesupport systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application
implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
Document Number: 001-88525 Rev. *B
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