IMP User Manual/Tech Ref Datasheet by ARTESYN / Advanced Energy

5 ¢ EMERSON. Network Power
Technical Reference Note
Embedded Power for
Business-Critical Continuity
APPLICATION OVERVIEW:
iMP USB-to-I2C DLL User's Manual
PRODUCT:
iMP SERIES
DESCRIPTION:
ABOUT THE DLL
There are two available DLL files available for use with the USB-to-I2C adapter, each using a different
function calling convention. Aside from the function calling convention, there are no other differences
between the two DLL. Similar functions are available for both DLL. The two DLL files are:
iMpDll.dll – Uses C Calling; Calling function cleans the stack
ail_HID_std.dll – Uses Standard Calling; Called function cleans the stack
To be able to use applications using the DLL, the DLL should be copied in the System32 folder located at
the Windows directory (Default: Windows\System32).
Rev. 0.0
http://www.semicenductors.ghi‘ipscom/buses/iZc/
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I²C PROTOCOL
GENERAL CHARACTERISTICS
The I²C protocol allows data to be transferred between devices using two open-drain (or open-collector)
bi-directional lines. One line is the serial clock (SCL) and the other is the serial data (SDA). The bus
master generates the Start conditions, the clock signals on SCL, as well as the Stop condition. An
acknowledge (ACK) is transmitted by the receiving device on the bus after each byte is sent.
BIT TRANSFER
Data on SDA must be stable while SCL is high. The state of SDA when SCL is high determines the logic
level of the transmitted data bit.
START AND STOP CONDITIONS
Within the procedure of the I²C bus, unique situations arise which are defined as START and STOP
conditions. A HIGH to LOW transition on the SDA line while SCL is HIGH is one such unique case. This
situation indicates a START condition. A LOW to HIGH transition on the SDA line while SCL is HIGH
defines a STOP condition. The master always generates START and STOP conditions. The bus is
considered to be busy after the START condition. The bus is considered to be free again a certain time
after the STOP condition.
I²C ADDRESS
The first seven bits of an I²C transmission, after a Start condition, make up the slave address. The eighth
bit (or the least significant bit) is the R/W bit that determines the direction of the message.
A '0' in the least significant position of the first byte means that the master will WRITE information
to the selected slave. A '1' in this position means that the master will READ information from the slave.
When an I²C address is sent, each device in a system compares the first seven bits after the START
condition with its own address. If they match, the device considers itself addressed by the master as a
slave-receiver or slave-transmitter, depending on the R/W bit.
SUBADDRESS
When an I²C device contains more than one register, the various registers are generally accessed using a
subaddress that is sent following the device address (see the I2CWriteArray and I2CReadArray sections
below). The subaddress acts like a pointer to the register that needs to be accessed.
DATA TRANSFER
Every byte on the SDA line must be 8-bits long. The number of bytes that can be transmitted per transfer
is unrestricted. Each byte must also be followed by an acknowledge bit. Data is transferred with the
most significant bit first. If a receiver can’t receive another complete byte of data until it has performed
some other function, it can hold the clock line SCL low to force the transmitter into a wait state.
ACKNOWLEDGE
The Acknowledge related clock pulse is generated by the master. The transmitter releases the SDA line
during the acknowledge clock pulse. The receiver must pull down the SDA line during the acknowledge
clock pulse so that it remains stable low during the high period of the clock pulse.
The master-receiver signals the end of a read by not acknowledging the last byte it requires.
I²C BUS DOCUMENTATION
The complete I²C Bus specification can be found at http://www.semiconductors.philips.com/buses/i2c/.
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SYSTEM REQUIREMENTS
• PC-compatible system
• USB port (1.1 or 2.0 compatible)
• Microsoft Windows 98(SE), ME, 2000 or XP
INSTALLATION
The USB-to-I2C adapter is an HID class device and requires no driver installation to use. The built in HID
driver of the operating is used for the driver. Once the adapter is plugged on the USB port, detection can
be confirmed in the Device Manager. Upon successful detection of the adapter, an HID-compliant device
will be added as seen in Figure 1.
Figure 1. Device Manager when Adapter is detected
4. MPUSBGetIZCFrequency Returns I20 lrequency of U
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AVAILABLE FUNCTIONS
1. MPUReset
Resets the USB-to-I2C Adapter.
Prototype:
unsigned char MPUReset(void)
Input Parameters: None
Output Parameter: Returns 0 on a successful reset
Returns 0xFF if an error occurred
2. MPUSBGetDLLVersion
Returns current DLL version.
Prototype:
unsigned short MPUSBGetDLLVersion (void)
Input Parameters: None
Output Parameter: Returns unsigned int interpreted as follows:
MSB – Major version
LSB – Minor Version
3. MPUSBGetDeviceVersion
Returns USB-to-I2C Adapter firmware version.
Prototype:
unsigned short MPUSBGetDeviceVersion (void)
Input Parameters: None
Output Parameter: Returns unsigned int interpreted as follows:
MSB – Major version
LSB – Minor Version
4. MPUSBGetI2CFrequency
Returns I2C frequency of USB-to-I2C Adapter is currently operating at.
Prototype:
unsigned integer MPUSBGetI2CFrequency (void)
Input Parameters: None
Output Parameter: Returns I2C frequency
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5. MPUSBSetI2CFrequency
Sets current I2C frequency of USB-to-I2C Adapter to desired frequency. Allowed frequency is
from 10 kHz to 400 kHz. Attempting to set I2C frequency below/above allowable frequencies will
set frequency to minimum/maximum allowable frequency.
Prototype:
unsigned integer MPUSBSetI2CFrequency (unsigned int frequency)
Input Parameters: frequency - desired I2C frequency
Output Parameter: Returns actual I2C frequency set
6. MPUI2CWrite
Performs I2C write to a destination address. The number of bytes to be sent must be stated, as
well as the pointer to the memory location of the first byte to be sent. It must also be stated
whether to include a stop bit will be sent at the end of transmition or not.
S Address W A nBytes of Data A P
Prototype:
unsigned char MPUI2CWrite (unsigned char address,
unsigned short nBytes,
*unsigned char WriteData,
unsigned short SendStop)
Input Parameters: address – Destination I2C address (7-bit)
nBytes – Number of bytes to send (maximum of 60 bytes)
WriteData – Memory address of location of 1st byte to be sent
SendStop – Set to ‘1’ to transmit stop bit
Set to ‘0’ to not transmit stop bit
Output Parameter: Returns error code:
0x00 – No error
0x01 – Address NACK
0x02 – Data NACK
0x07 – Arbitration lost
0x81 – Size overflow
0xFF – USB-to-I2C not detected
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7. MPUI2CRead
Performs I2C read to a destination address. The number of bytes to be received must be stated,
as well as the pointer to the memory location where the first byte received will be stored. It must
also be stated whether to include a stop bit will be sent at the end of transmition or not.
S Address R A nBytes of Data A P
Prototype:
unsigned char MPUI2CRead (unsigned char address,
unsigned short nBytes,
*unsigned char ReadData,
unsigned short SendStop)
Input Parameters: address – Source I2C address (7-bit)
nBytes – Number of bytes to receive (maximum of 60 bytes)
Readata – Memory address of location where 1st byte to be
received will be stored
SendStop – Set to ‘1’ to transmit stop bit
Set to ‘0’ to not transmit stop bit
Output Parameter: Returns error code:
0x00 – No error
0x01 – Address NACK
0x02 – Data NACK
0x07 – Arbitration lost
0x81 – Size overflow
0xFF – USB-to-I2C not detected
8. MPUI2CWriteArray
Performs I2C write array to a destination address, is an I2C write wherein the 1st byte sent is the
sub-address (ie in PMBus, the subaddress will be the PMBus command), followed a certain
number of bytes, with a stop bit at the end.
S Address W A Sub-Address A nBytes of Data A P
Prototype:
unsigned char MPUI2CWriteArray (unsigned char address,
unsigned char subaddress,
unsigned short nBytes,
*unsigned char WriteData)
Input Parameters: address – Destination I2C address
subaddress – Destination sub-address
nBytes – Number of bytes to send (maximum of 60 bytes)
WriteData – Memory address of location of 1st byte to be sent
Output Parameter: Returns error code:
0x00 – No error
0x01 – Address NACK
0x02 – Data NACK
0x07 – Arbitration lost
0x81 – Size overflow
0xFF – USB-to-I2C not detected
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9. MPUI2CReadArray
Performs I2C read array to a destination address, wherein an I2C write sending one byte of sub-
address (ie in PMBus, the subaddress will be the PMBus command) is performed (without stop
bit), followed by an I2C read of a certain number of bytes. A stop bit is then sent at the end.
S Address W A Sub-Address A S Address A nBytes of Data A Stop?
Prototype:
unsigned char MPUI2CReadArray (unsigned char address,
unsigned char subaddress,
unsigned short nBytes,
*unsigned char ReadData)
Input Parameters: address – Source I2C address
subaddress – Source sub-address
nBytes – Number of bytes to receive (maximum of 60 bytes)
ReadData – Memory address of location where 1st byte to be
received will be stored
Output Parameter: Returns error code:
0x00 – No error
0x01 – Address NACK
0x02 – Data NACK
0x07 – Arbitration lost
0x81 – Size overflow
0xFF – USB-to-I2C not detected