Application Note
AN_190
C232HM MPSSE Cable in USB to
I2C/SMBus interface
Version 1.0
Issue Date: 2011-10-17
This application note demonstrates the use of the libMPSSE-I2C library in
conjunction with an FTDI C232HM cable and a Maxim MAX17061 LED Controller
Evaluation Board. All source code required is also included.
Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the user agrees
to defend, indemnify and hold harmless FTDI from any and all damages, claims, suits or expense resulting
from such use.
Future Technology Devices International Limited (FTDI)
Unit 1, 2 Seaward Place, Glasgow G41 1HH, United Kingdom
Tel.: +44 (0) 141 429 2777 Fax: + 44 (0) 141 429 2758
Web Site: http://ftdichip.com
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
Table of Contents
1
2
Introduction .................................................................... 2
1.1
Scope ........................................................................................ 2
1.2
I2C and SMBus background ....................................................... 2
Equipment ....................................................................... 3
2.1.1
FTDI C232HM cable and D2XX Device Drivers ............................................... 3
2.1.2
MAX17061 EVALUATION KIT+..................................................................... 3
2.1.3
Power Supply ............................................................................................ 3
2.1.4
Source Code , Compiler and Executable ....................................................... 3
2.1.5
Libraries and Device Drivers ....................................................................... 3
2.1.6
Additional items ........................................................................................ 3
2.2
Configuration & Setup ............................................................... 4
3
Example Program Execution ........................................... 6
4
Example Program Discussion .......................................... 7
4.1
Visual Studio 2010 Preparation................................................. 7
4.2
Code discussion ........................................................................ 9
5
Full Application Program Listing ................................... 12
6
Conclusion .................................................................... 17
7
Contact Information ...................................................... 18
Appendix A – References ................................................... 19
Document & Website References .................................................... 19
Acronyms and Abbreviations ........................................................... 19
Appendix B – List of Tables & Figures ................................ 20
Appendix C – Revision History ........................................... 21
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Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
1 Introduction
This application note demonstrates controlling an LED backlight over a USB connection utilizing the FTDI
C232HM cable. The cable contains the FTDI FT232H IC and the LED backlight controller is the Maxim
MAX17061 IC. The libMPSSE-I2C library is used in a Microsoft Visual Studio C++ console application that
controls the FT232H which, in turn, sends commands over a SMBus to the MAX17061. The MAX17061
finally controls the power to the LEDs.
The connection from the USB port to the LEDs is controlled by a console application written in Visual C++
which links to the libMPSSE library and performs the following functions:
Identify the FTDI devices and open the first C232HM cable found
Initialize the SMBus
Read and write the various registers of the MAX17061
Control the brightness of the LEDs that are connected to the MAX17061
1.1 Scope
This document is meant to function as an introduction to the use of the FTDI C232HM cable in
conjunction with I2C and SMBus devices. Familiarity with installing the FTDI device drivers and using
Microsoft Visual Studio 2010 is assumed. Users should reference the respective standards and
datasheets for additional information.
1.2 I2C and SMBus background
I2C and SMBus are very similar. They are both meant to exchange information among ICs within a
single system. Both operate with two signals referenced to ground. SDA is the bi-directional data signal
and SCL is the synchronizing clock. Table 1.1 shows some of the major similarities and differences:
Feature
I2C
SMBus
Signals
SDA and SCL
SDA and SCL
Voltage Levels
<2V to >10V
3V to 5V
Multi-device
Yes
Yes
Data Format
8 data bits followed by ACK
8 data bits followed by ACK
Speed
0bps through 3.4Mbps
10Kbps through 100Kbps
Addressing
Fixed
Table 1.1 I2C & SMBus Features
Fixed and Dynamic
The FTDI devices which contain an MPSSE (Multi-Protocol Synchronous Serial Engine) can interact with
I2C and SMBus, as well as other serial protocols such as SPI and JTAG. As noted above, the C232HM
cable contains the FT232H. Other FTDI MPSSE devices are the FT2232D, FT2232H and FT4232H. With
slight modifications the code in this application note can be used with any of these ICs.
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2 Equipment
Several items are required to duplicate the program and results of this application note.
2.1.1 FTDI C232HM cable and D2XX Device Drivers
The C232HM-EDHSL-0 cable is used with this application note. The 5VDC power output from the cable is
required for the MAX17061 evaluation board. The “flying leads” accept a 0.025” square post header on
0.1” centers. The USB end of the cable contains the FT232H necessary to carry out the MPSSE
commands.
When installing the device drivers for the cable, ensure the D2XX device drivers are enabled. Microsoft
Windows device drivers install with both D2XX and VCP drivers enabled by default. A Linux version of the
libMPSSE libraries is also available. Within Linux, the VCP drivers may need disabled prior to installing
the D2XX drivers. Refer to the device driver installation guides on the FTDI Website.
2.1.2 MAX17061 EVALUATION KIT+
The MAX17061 EVALUATION KIT+ (hereafter referred to as the MAX17061 board) is an evaluation board
with the MAX17061 IC, power supply circuitry, 40 white LEDs and an interface connector.
2.1.3 Power Supply
A power supply capable of generating 12VDC at a minimum of 500mA is used as a power source for the
LEDs.
2.1.4 Source Code , Compiler and Executable
The program explained within this application note can be downloaded from the following location
http://www.ftdichip.com/Support/SoftwareExamples/MPSSE/AN_190_Source_Code.zip
The source code is written within the Microsoft Visual Studio 2010 development environment. Download
and extract the files to a folder on the system hard drive. A compiled executable is also included in this
download.
Note that the software and source code is provided as an example only and is not guaranteed or
supported by FTDI.
2.1.5 Libraries and Device Drivers
The example program relies on the FTDI D2XX Device Driver and libMPSSE-I2C library. Download and
extract the ZIP file contents to folders on the host system hard drive. The necessary files are also
contained with the source code for this application note.
2.1.6 Additional items
A pair of wires for connection to the power supply
Two 0603-size surface-mount 3.3KΩ resistors
One 5-position 0.1” pin-header with long pins is needed. A break-away style is preferred since
this will need modified as noted below.
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2.2 Configuration & Setup
1) The MAX17061 board provides locations for pull-up resistors on the SCL and SDA signals. These
locations are not populated by default since the exact configuration of the SMBus is unknown.
For the purposes of this demonstration, a “middle-of-the-road” value of 3.3KΩ is chosen. Solder
these two 3.3KΩ resistors in locations R8 and R9 on the MAX17061 board.
2) Solder wires to the VIN and GND tabs toward the top of the MAX17061 board. Connect these
wires to the 12VDC power supply. Note that VIN is positive. Do not turn on the 12V power
supply at this time.
3) Configure the MAX17061 board jumpers as noted on page 3 of its datasheet (Quick Start /
Procedure).
4) Break the header apart into two 2-pin sections and one 1-pin section. Take one of the 2-pin
sections and bend one pin to touch the other as close to the plastic as possible. Solder this
connection point:
Figure 2.1 Modified 2-pin Header Soldered To Form SDA (DO and DI connection)
5) Using the pin headers, connect the C232HM flying leads to the MAX17061 board as follows:
CH232M
Color
Cable
Signal
Type /
Direction
MAX17061 Eval
Board, J1 Pin
Using
Signal
Name
Red
VCC
Power
1
Single-pin
VDD
Green
TDO/DI
Input
TDI/DO
Output
2
Modified 2-pin
SDA
Yellow
Black
GND
Ground
3
Unmodified 2-pin
GND
Orange
TCK/SK
Output
4
Unmodified 2-pin
SCL
Others
Unused
Unused
N/C
N/A
Table 2.1 C232HM - MAC17061 Board Connection
The connection is shown in Figure 2.2:
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Figure 2.2 C232HM to MAX17061 Evaluation Board Connection
6) Connect the C232HM cable to the host computer.
7) Turn on the 12V power supply.
At this point, everything is prepared to control the MAX17061 with the example program. The LEDs are
directional and very bright. It is suggested to point the bottom of the Maxim board away from your eyes.
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3 Example Program Execution
The source code has been compiled into an executable program that can be executed directly on the host
PC without the need for the development tools. After taking the steps above to install and configure the
hardware, navigate to the Release directory of the extracted folder and double-click on
“AN_190_C232HM_libMPSSE_I2C.exe” to run the program as shown in Figure 3.1.
Figure 3.1 Example Program Location
The program will open a console window and step through each of the code sections as shown in Figure
3.2.
Figure 3.2 Executing the Example Program
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4 Example Program Discussion
Important aspects of the application program are discussed in the following sections.
4.1 Visual Studio 2010 Preparation
Create a new console application. Open the project properties and view the Linker Input properties:
Figure 4.1 Visual Studio Linker Options
The first entry is called “Additional Dependencies”.
It should be noted that in most cases, only the libMPSSE library would need to be added. Since this
application uses the FT232H, it takes advantage of a new MPSSE function that is not yet available
through the libMPSSE library at the time of this writing. This function (0x9E) configures the FT232H to
only drive an output when its value is zero, then tri-state when the value is a one. The function was
added specifically for I2C and SMBus use. Future releases of the libMPSSE will include settings for this
feature. At that time, the requirement to specifically add the “ftd2xx.lib” reference will be eliminated. If
this code is used with earlier MPSSE devices (FT2232D, FT2232H or FT4232H), “only drive zero” is not
supported.
Edit this field to add the following items:
”libmpsse.a” and “ftd2xx.lib”:
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Figure 4.2 LibMPSSE & FTD2XX Library Dependencies
Click OK on this and the property page to accept the changes.
Repeat this for both “Debug” and “Release” configurations.
In addition to configuring the libraries, both configurations need to have optimization disabled. Within
the project properties, select the Release configuration, and then navigate to the General properties. The
last item is “Whole Program Optimization”. Select “No Whole Program Optimization”. Repeat for the
Debug configuration.
Figure 4.3 Release Build General Properties
Save the project.
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When a Visual Studio project is created, the base directory of the project contains the “solution” file
(name.sln). This base folder also holds a history and other project related files. Within the base folder
are several other folders. One typically has the same name as the solution. In this example, the project
was copied to the root of the hard drive:
C:\AN_190_C232HM_libMPSSE_I2C
Library files which are referenced by name only are then located in the folder named the same as the
solution:
C:\AN_190_C232HM_libMPSSE_I2C\AN_190_C232HM_libMPSSE_I2C
Copy the library and DLL files from the respective driver and library downloads to this folder of the
project. The required files are:
ftd2xx.h, ftd2xx.lib, libMPSSE.a, libMPSSE.dll, libMPSSE_definitions.cpp and libMPSSE_i2c.h
The other files shown here are generated by Visual Studio 2010.
Figure 4.4 Library Files
At this point, code can be written, compiled and linked with the necessary files. A discussion of library
paths and project options is beyond the scope of this application note.
A complete Visual Studio 2010 project is available from the FTDI Website by clicking on the following link
http://www.ftdichip.com/Support/SoftwareExamples/MPSSE/AN_190_Source_Code.zip
4.2 Code discussion
This is a console application (aka Command Prompt Window) intended to show the flow of information
between the host PC and the MAX17061 LED controller. In addition to the usual “windows.h” and
“stdio.h” headers, this application uses “conio.h” for the getchar() call.
// Included by Visual Studio for a standard console app
#include "stdafx.h"
// Include standard windows and C++ headers
#include <windows.h>
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#include <stdio.h>
#include <conio.h>
// Include the header files for the base FTDI and libMPSSE libraries
#include "ftd2xx.h"
#include "libMPSSE_i2c.h"
Several variables are declared but not shown here. There are several specific to the libMPSSE library:
// libMPSSE-related variables
FT_STATUS i2cStatus = 0;
uint32 i2cNumChannels = 0;
FT_DEVICE_LIST_INFO_NODE i2cChannelInfo[4];
FT_HANDLE i2cHandle;
ChannelConfig i2cChannel;
FT_STATUS refers to the error codes returned by both the libMPSSE and D2XX calls.
FT_DEVICE_LIST_INFO_NODE refers to a structure containing information about an FT-series device,
including the device description, USB Vendor and Product IDs and other information.
FT_HANDLE refers to the system handle that is used throughout the program to select the correct device.
ChannelConfig refers to a structure containing I2C setup information such as bit rate, latency timer and
clock type.
The MAX17061 responds to two of the several defined SMBus command types: Write Byte and Read
Byte.
Write Byte is handled directly through a single libMPSSE I2C_DeviceWrite call. An address is specified
along with a data buffer containing two bytes: “command” and “data”. The resulting transmission sends
these three bytes in order, with an ACK/NACK response from the MAX17061 between each one. The
entire transmission is flanked by a START condition at the beginning and a STOP condition at the end.
S
(Start)
Addr
(7-bit)
R/W
(1-bit)
ACK
(1-bit)
Command
(8-bit)
ACK
(1-bit)
Data
(8-bit)
ACK
(1-bit)
P
(Stop)
Figure 4.5 SMBus Write Byte
Cells with a clear background indicate SDA driven by the C232HM cable. Cells with a gray background
indicate SDA driven by the MAX17061.
The following code shows a single write to set the brightness of the MAX17061:
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x00;// brightness
i2cData[i2cNumBytesToTx++] = 0x00;// lowest level, about 2.5% according to the MAX17061 datasheet
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x03);
Read Byte is just a bit more complex. As with Write Byte, the transmission begins with a START
condition followed by the address and command, then another START condition and the address are
transmitted again followed by the MAX17061 sending it’s byte of data and finally the STOP condition.
S
(Start)
S
(Start)
Addr
(7-bit)
Addr
(7-bit)
R/W
(1-bit)
R/W
(1-bit)
ACK
(1-bit)
ACK
(1-bit)
Command
(8-bit)
Data
(8-bit)
ACK
(1-bit)
ACK
(1-bit)
P
(Stop)
Figure 4.6 SMBus Read Byte
As with SMBus Write Byte, cells with a clear background indicate SDA driven by the C232HM cable. Cells
with a gray background indicate SDA driven by the MAX17061.
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This sequence can be accomplished with an I2C_DeviceWrite call directly followed by an I2C_DeviceRead
call as shown in this read of the status register:
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x02; // Status register
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x01);
i2cNumBytesToRx = 1;
// Read one byte
i2cStatus += I2C_DeviceRead(i2cHandle, i2cAddr, i2cNumBytesToRx, &i2cData[0], &i2cNumBytesRxd, 0x03);
Notice the last argument of the write is 0x01. This causes the sequence to begin with the START but
don’t include the STOP when done. The bus remains active until the the read is complete with the last
argument of 0x03. The read sends another START and completes with a STOP. Although these calls are
initially geared toward a more general I2C use, it’s shown here that they can be combined to satisfy
SMBus command structures as well.
The application reads and writes each of the available registers of the MAX17061, ultimately causing the
LEDs to turn on, ramp from low to full brightness and back down to low, and then finally close the port
and exit.
Although this application note shows a Visual Studio application, similar code could be complied on a
Linux system with the Linux version of the libMPSSE.a library and D2XX device drivers.
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5 Full Application Program Listing
// AN_190_C232HM_libMPSSE_I2C.cpp : Defines the entry point for the console application.
// Note that the software and source code is provided as an example only
// and is not guaranteed or supported by FTDI.
/*
========================================================================
Copy the following files from the libMPSSE folder to your project folder
- ftd2xx.h
// This is the base FTDI USB header
- libMPSSE.h
// This is the header to define the libMPSSE calls
- libMPSSE.dll // This is the DLL
- libMPSSE.a
// This is the libarary (as opposed to a .lib file)
- ftd2xx.lib
// This is the main D2XX library - only needed to set
// the "only drive zero" feature of the FT232H
Next, open the Project menu item and select <Project Name> Properties
Under the Linker tree, select Input.
Add libmpsse.a and ftd2xx.lib to the Additional Dependencies
========================================================================
*/
// Included by Visual Studio for a standard console app
#include "stdafx.h"
// Include standard windows and C++ headers
#include <windows.h>
#include <stdio.h>
#include <conio.h>
// Include the header files for the base FTDI and libMPSSE libraries
#include "ftd2xx.h"
#include "libMPSSE_i2c.h"
int _tmain(int argc, _TCHAR* argv[])
{
// General variables
uint32 i, index;
unsigned char j;
// MAX17061 variable for SMBus address
uint32 i2cAddr;
// libMPSSE-related variables
FT_STATUS i2cStatus = 0;
uint32 i2cNumChannels = 0;
FT_DEVICE_LIST_INFO_NODE i2cChannelInfo[4];
FT_HANDLE i2cHandle;
ChannelConfig i2cChannel;
// This is the I2C address (fixed at 0101100 for the MAX17061
// Note this is right-justified for the libMPSSE calls. Bit 7 is unused.)
i2cAddr = 0x2C;
// This is the default address
unsigned char i2cData[16];
uint32 i2cNumBytesToTx;
uint32 i2cNumBytesTxd;
//
//
//
//
Initialize a data buffer
Initialize a counter for the buffer
Initialize another counter for the number of
bytes actually sent
uint32 i2cNumBytesToRx;
uint32 i2cNumBytesRxd;
// Initialize the MPSSE libraries
Init_libMPSSE();
// First, find out how many devices are capable of MPSSE commands
i2cStatus = I2C_GetNumChannels(&i2cNumChannels);
if (i2cStatus)
// Any value besides zero is an error
{
printf("ERROR %X - Cannot execute I2C_GenNumChannels. \nPress <Enter> to continue.\n",
i2cStatus);
getchar();
return 1;
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}
if (i2cNumChannels > 4)
{
printf("This program can only identify up to 4 MPSSE devices\n");
getchar();
return 1;
}
if (i2cNumChannels < 1)
{
printf("No C232HM cables were found\n");
getchar();
return 1;
}
// Next, get the information about each one
for (i=0; i < i2cNumChannels; i++)
{
// Get the information from each MPSSE device
i2cStatus = I2C_GetChannelInfo(i, &i2cChannelInfo[i]);
if (i2cStatus)
{
printf("ERROR %X - Cannot execute I2C_GetChannelInfo.
continue.\n", i2cStatus);
getchar();
return 1;
}
\nPress <Enter> to
// If it's one of the C232HM calbes, then stop - we'll take the first one we find
if ((i2cChannelInfo[i].Description == "CH232HM-EDHSL-0") | (i2cChannelInfo[i].Description ==
"CH232HM-DDHSL-0"))
break;
}
index = i - 1;
// The index is zero-based
// Nofity what was found and what we're using
printf("\n");
printf(" %d MPSSE devices found. Device %d will be used. \n", i2cNumChannels, index);
printf("\n");
// We found the cable, now let's open it
i2cStatus = I2C_OpenChannel(index, &i2cHandle);
if (i2cStatus)
{
printf("ERROR %X - Cannot execute I2C_OpenChannel.
i2cStatus);
getchar();
return 1;
}
// Set up the various I2C parameters
i2cChannel.ClockRate = I2C_CLOCK_STANDARD_MODE;
i2cChannel.LatencyTimer = 1;
i2cChannel.Options = 0;
\nPress <Enter> to continue.\n",
// 100Kbps
// 1mS latency timer
// 3-phase clocking enabled
i2cStatus = I2C_InitChannel(i2cHandle, &i2cChannel);
if (i2cStatus)
{
printf("ERROR %X - Cannot execute I2C_InitChannel.
i2cStatus);
getchar();
return 1;
}
\nPress <Enter> to continue.\n",
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// For the FT232H, the "write on zero only" command is not yet implemented.
// These commands will enable this feature
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x9E;
// Enable write zero only
i2cData[i2cNumBytesToTx++] = 0x03;
// ADBUS0 and ADBUS1 only
i2cData[i2cNumBytesToTx++] = 0x00;
unsigned long sent;
FT_Write(i2cHandle, i2cData, i2cNumBytesToTx, &sent);
// Now get the read-only registers of the MAX17061 device
// The MAX17061 uses SMBus Read Byte and Write Byte commands. This requires a combination of
// two i2cMPSSE commands. The first is a write to send the address and "command" (or register
// address).
// The second is the actual read. Note that the first has no stop condition, but the second has
// another start condition
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x03;
// ID register
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x01);
i2cNumBytesToRx = 1;
i2cStatus += I2C_DeviceRead(i2cHandle, i2cAddr, i2cNumBytesToRx, &i2cData[0], &i2cNumBytesRxd, 0x03);
if (i2cStatus)
{
printf("ERROR %X - Cannot read MAX17061 ID register. \nPress <Enter> to continue.\n",
i2cStatus);
getchar();
return 1;
}
printf(" The ID register value is 0x%X\n", i2cData[0]);
printf("\n");
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x02;
// Status register
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x01);
i2cNumBytesToRx = 1;
i2cStatus += I2C_DeviceRead(i2cHandle, i2cAddr, i2cNumBytesToRx, &i2cData[0], &i2cNumBytesRxd, 0x03);
if (i2cStatus)
{
printf("ERROR %X - Cannot read MAX17061 Status register. \nPress <Enter> to continue.\n",
i2cStatus);
getchar();
return 1;
}
printf(" The Status register value is 0x%X\n", i2cData[0]);
printf("\n");
// Now let's set up the brightness to the lowest level so we're not blinded
// As noted, the MAX17061 uses SMBus Read Byte and Write Byte.
// accomplished by a single libMPSSE write
Here only the Write Byte, which is
i2cNumBytesToTx = 0;
i2cData[i2cNumBytesToTx++] = 0x00;
i2cData[i2cNumBytesToTx++] = 0x00;
// Initialize data counter
// brightness
// lowest level, about 2.5% according to the
// MAX17061 datasheet
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x03);
if (i2cStatus)
{
printf("ERROR %X - Cannot set MAX17061 brightness register. \nPress <Enter> to continue.\n",
i2cStatus);
getchar();
return 1;
}
// Finally, we'll turn on the LEDs
i2cNumBytesToTx = 0;
i2cData[i2cNumBytesToTx++] = 0x01;
i2cData[i2cNumBytesToTx++] = 0x01;
// Initialize data counter
// Control Reg
// Turn on LEDs
14
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x03);
if (i2cStatus)
{
printf("ERROR %H - Cannot set MAX17061 control register. \nPress <Enter> to continue.\n",
i2cStatus);
getchar();
return 1;
}
// The brightness can be adjusted on-the-fly, so lets go from dim to bright to dim
printf(" Ramping up LED brightness...\n");
printf("\n");
for (j = 0; j < 240 ; j = j + 10)
{
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x00;
// brightness
i2cData[i2cNumBytesToTx++] = j + 10;
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd,
0x03);
if (i2cStatus)
{
printf("Loop Number %X, ERROR %X - Cannot set MAX17061 brightness register in rampup. \nPress <Enter> to continue.\n", j, i2cStatus);
getchar();
return 1;
}
Sleep(100);
}
printf(" Ramping down LED brightness...\n");
printf("\n");
for (j = 250; j > 0; j = j - 10)
{
i2cNumBytesToTx = 0;
// Initialize data counter
i2cData[i2cNumBytesToTx++] = 0x00;
// brightness
i2cData[i2cNumBytesToTx++] = j;
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd,
0x03);
if (i2cStatus)
{
printf("Loop Number %X, ERROR %X - Cannot set MAX17061 brightness register in rampdown. \nPress <Enter> to continue.\n", j, i2cStatus);
getchar();
return 1;
}
Sleep(100);
}
// Turn off the LEDs
printf(" Turning off the LEDs\n");
printf("\n");
i2cNumBytesToTx = 0;
i2cData[i2cNumBytesToTx++] = 0x01;
i2cData[i2cNumBytesToTx++] = 0x00;
// Initialize data counter
// Control Reg
// Turn off LEDs
i2cStatus = I2C_DeviceWrite(i2cHandle, i2cAddr, i2cNumBytesToTx, i2cData, &i2cNumBytesTxd, 0x03);
if (i2cStatus)
{
printf("ERROR %X - Cannot set MAX17061 control register. \nPress <Enter> to continue.\n",
i2cStatus);
getchar();
return 1;
}
15
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
// Time to close up shop - close the channel, then ...
printf(" Closing the CH232M MPSSE channel\n");
printf("\n");
i2cStatus = I2C_CloseChannel(i2cHandle);
if (i2cStatus)
{
printf("ERROR %X - Cannot execute I2C_CloseChannel.
i2cStatus);
getchar();
return 1;
}
Clearance No.: FTDI# 226
\nPress <Enter> to continue.\n",
// ... close out the MPSSE libraries
printf(" Cleaning up the libMPSSE library\n");
printf("\n");
Cleanup_libMPSSE();
printf(" Exit program.
printf("\n");
getchar();
return 0;
\nPress <Enter> to continue.\n");
}
16
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
6 Conclusion
The FTDI ICs which incorporate the Multi-Protocol Synchronous Serial Engine provide a versatile interface
to SPI, JTAG and I2C devices. This application note demonstrated the I2C functionality and specifically
the SMBus customization of the I2C protocol through the use of the libMPSSE-I2C Application
Programming Interface (API).
For SPI use, readers are encouraged to refer to Application Note AN_188, Using the C232HM MPSSE
Cable in USB to SPI Interface for using the same cable in a SPI application with the libMPSSE-SPI API.
Basic JTAG operation is shown in AN_129, FTDI Hi-Speed USB to JTAG Example.
17
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
7 Contact Information
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Web Site
http://ftdichip.com
Distributor and Sales Representatives
Please visit the Sales Network page of the FTDI Web site for the contact details of our distributor(s) and sales
representative(s) in your country.
System and equipment manufacturers and designers are responsible to ensure that their systems, and any Future Technology Devices
International Ltd (FTDI) devices incorporated in their systems, meet all applicable safety, regulatory and system-level performance
requirements. All application-related information in this document (including application descriptions, suggested FTDI devices and other
materials) is provided for reference only. While FTDI has taken care to assure it is accurate, this information is subject to customer
confirmation, and FTDI disclaims all liability for system designs and for any applications assistance provided by FTDI. Use of FTDI
devices in life support and/or safety applications is entirely at the user’s risk, and the user agrees to defend, indemnify and hold
harmless FTDI from any and all damages, claims, suits or expense resulting from such use. This document is subject to change without
notice. No freedom to use patents or other intellectual property rights is implied by the publication of this document. Neither the whole
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Seaward Place, Centurion Business Park, Glasgow G41 1HH, United Kingdom. Scotland Registered Company Number: SC136640
18
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
Appendix A – References
Document & Website References
Source code for this application note,
http://www.ftdichip.com/Support/SoftwareExamples/MPSSE/AN_190_Source_Code.zip
I2C Specification, NXP Corporation
SMBus Specification, System Management Interface Forum, Inc.
C232HM MPSSE Cable Datasheet, FTDI Ltd.
FT232H Single Channel Hi-Speed USB to Multipurpose UART/FIFO IC Datasheet, FTDI Ltd.
AN_177 User Guide for libMPSSE-I2C, FTDI Ltd.
AN_108 Command Processor For MPSSE and MCU Host Bus Emulation Modes, FTDI Ltd.
D2XX Programmer’s Guide, FTDI Ltd.
FTDI D2XX Device Drivers, FTDI Ltd.
MAX17061 Product Page, Maxim Integrated Products
MAX17061 Evaluation Kit Product Page, Maxim Integrated Products
Acronyms and Abbreviations
Terms
USB
Description
Universal Serial Bus
USB-IF
USB Implementers Forum
MPSSE
Multi-Protocol Synchronous Serial Engine
LED
Light Emitting Diode
API
Application Programming Interface
SPI
Serial Peripheral Interface
JTAG
I2C
Joint Test Action Group
Inter-Integrated Circuit bus
UART
Universal Asynchronous Receiver/Transmitter
FIFO
First In First Out
SMBus
IC
DLL
System Management Bus
Integrated Circuit
Dynamically Linked Library
19
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
Appendix B – List of Tables & Figures
List of Tables
Table 1.1 I2C & SMBus Features ................................................................................. 2
Table 2.1 C232HM - MAC17061 Board Connection ...................................................... 4
List of Figures
Figure 2.1 Modified 2-pin Header Soldered To Form SDA (DO and DI connection) ..... 4
Figure 2.2 C232HM to MAX17061 Evaluation Board Connection ................................. 5
Figure 3.1 Example Program Location ........................................................................ 6
Figure 3.2 Executing the Example Program ................................................................ 6
Figure 4.1 Visual Studio Linker Options ...................................................................... 7
Figure 4.2 LibMPSSE & FTD2XX Library Dependencies ................................................ 8
Figure 4.3 Release Build General Properties ............................................................... 8
Figure 4.4 Library Files ............................................................................................... 9
Figure 4.5 SMBus Write Byte .................................................................................... 10
Figure 4.6 SMBus Read Byte ..................................................................................... 10
20
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
Version 1.0
Document Reference No.: FT_000515
Clearance No.: FTDI# 226
Appendix C – Revision History
Document Title:
Document Reference No.:
Clearance No.:
Product Link:
Document Feedback:
Revision
1.0
Changes
Initial Release
AN_190 C232HM MPSSE Cable in USB to I2C/SMBus interface
FT_000515
FTDI# 226
http://www.ftdichip.com/Products/Cables/USBMPSSE.htm
Send Feedback
Date
2011-10-17
21
Copyright © 2011 Future Technology Devices International Limited