19-2150; Rev 0; 8/01 MAX6900 Evaluation System Features ♦ Proven PC Board Layout ♦ Low-Voltage Operation ♦ Supply Current Monitoring ♦ Fully Assembled and Tested Ordering Information Order the complete EV system (MAX6900EVSYS) for comprehensive evaluation of the MAX6900 using a PC. Order the EV kit (MAX6900EVKIT) if the MAXSMBus module has already been purchased with a previous Maxim EV system, or for custom use in other µC-based systems. TEMP. RANGE INTERFACE MAX6900EVKIT PART 0°C to +70°C User supplied MAX6900EVSYS 0°C to +70°C Windows software Quick Start Component List REFERENCE QTY C1, C3, C4 3 0.1µF, 10V X7R ceramic capacitors C2, C5 2 10µF, 10V tantalum capacitors J1 1 2 x 10 right-angle socket SamTec SSW-110-02-S-D-RA JU1, JU2 2 2-pin jumpers R1, R2 0 Open (site for optional 4.7kΩ ±5% 1206 resistor) R3 1 49.9kΩ ±1% resistor Recommended Equipment DESCRIPTION U1 1 MAX6900EUT U2, U3 2 MAX3370EXK-T Y1 1 32.768kHz crystal, 12.5pF load capacitance Digi-Key X801-ND Y2 0 32.768kHz crystal, 12.5pF load capacitance None 1 PC board, MAX6900 EV kit None 1 3.5in software disk, MAX6900 EV kit Windows is a registered trademark of Microsoft Corp. I2C is a registered trademark of Philips Corp. Before you begin, the following equipment is needed: • Maxim MAX6900EVKIT and MAXSMBus interface board • 12VDC power supply (any supply voltage between +9V and +15V is acceptable) • Computer running Windows 98 • Spare parallel port • 25-pin I/O extension cable Connections and Setup 1) With the power off, connect the 12VDC power supply to the MAXSMBus board between POS9 and GND. The MAX6900 IC’s +5V supply comes from the MAXSMBus board. 2) Connect the boards together. 3) Connect the 25-pin I/O extension cable from the computer’s parallel port to the MAXSMBus board. The EV kit software uses a loopback connection to confirm that the correct port has been selected. 4) Install the EV system software on your computer by running the INSTALL.EXE program on the floppy disk. The program files are copied and icons are created for them in the Windows Start menu. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX6900 General Description The MAX6900 evaluation system (EV system) is a realtime clock evaluation system consisting of a MAX6900 evaluation kit (EV kit) and a Maxim MAXSMBus module. Windows® 98 software provides a handy user interface to exercise the features of the MAX6900. (Note: Windows NT/2000 requires additional driver software; contact factory.) This EV kit is intended to demonstrate the functionality and features of the MAX6900 real-time clock with an I2C™-compatible 2-wire interface. It is not designed to exercise the MAX6900 at its maximum serial bus interface speed. A typical bus interface speed is in the 90kHz range and depends upon the operating system and computer used. Evaluates: MAX6900 MAX6900 Evaluation System Table 1. Jumper Functions JUMPER POSITION JU1 Closed* FUNCTION JU1 Open JU2 Closed* The supply current-sensing resistor R3 is shorted, enabling communication with the real-time clock. JU2 Open The timekeeping supply current can be estimated by measuring voltage across R3. Communication is not possible in this state. VL = +5V from MAXSMBus module User-supplied VL ≤ +5V *An asterisk indicates a default configuration. 5) Ensure that the jumper settings are in the default position (Table 1). 6) Start the program by opening its icon in the Start menu. 7) Click on the Set from computer’s clock button to write the current time of day into the MAX6900. an optional surface-mount crystal. Only one crystal may be used. MAXSMBus Connector The MAXSMBus board connects to the device under test in accordance with Table 2. Troubleshooting 8) Observe the difference between the computer’s time and the MAX6900 time. Problem: Unable to communicate while measuring supply current. 9) Unplug the MAX6900EVSYS from the parallel port for long-term drift testing. Jumper JU2 must be closed to enable communication. Detailed Description of Hardware The MAX6900 (U1) is a real-time clock with RAM. The MAX3370 level translators (U2 and U3) are not required for normal operation of the MAX6900, but allow operation at supply voltages down to +2V, while still communicating with the MAXSMBus board, which is using +5V logic levels. See Figure 6, and refer to the MAX6900 data sheet. Detailed Description of Software The EV software provides access to all registers. The main timekeeping registers appear in the main screen, with other screens accessible from the View menu. To write to a single register, click on the appropriate register select button, set the desired value, and then click the Write button. Cyclic Burst Read must be disabled before you can write to a single register. To read a register, click on the appropriate register select button, and then click the Read button. Measuring Timekeeping Supply Current The MAX6900 is in standby mode whenever no commands are being sent. To measure the timekeeping supply current drawn in standby mode, first ensure that the main screen’s Cyclic Burst Read checkbox is not checked, remove the shunt from jumper JU2, and measure the voltage across resistor R3. A voltage drop of 10mV represents 200nA of timekeeping supply current. For active bus operation (serial bus activity), replace shunt JU2 to prevent excessive voltage drop across resistor R3. Surface-Mount Crystal The EV kit comes with a 1.1mm cylindrical tuning-fork crystal; however, the PC board layout accommodates 2 Main Screen The Read button reads the most recently selected timekeeping register. The Write button writes the most recently selected timekeeping register. The Burst Read button performs a Burst Read from the timekeeping registers (except Century). The Burst Write button performs a Burst Write to the timekeeping registers (except Century). The Set from computer’s clock button writes the PC’s time into the MAX6900. The Cyclic Burst Read checkbox tells the software to perform a Burst Read from the timekeeping registers, at a rate of approximately 4 times per second. Updates are shown in the register display, along with the difference between MAX6900 time and the host PC’s time (Figure 1). _______________________________________________________________________________________ MAX6900 Evaluation System NAME I2C INTERFACE 1 +5V Optional +5V supply 2 GND Ground 3 SDA SDA 4 GND Ground 5 GND Ground 6 GND Ground PIN 7 SCL SCL 8 GND Ground 9 SMBSUS No connection 10 GND Ground 11 ALERT No connection 12 GND Ground 13 ALERT2 No connection 14 GND Ground 15 OUTA No connection 16 GND Ground 17 OUTB No connection 18 GND Ground 19 GND Ground 20 RAW PWR No connection Note: Odd-numbered pins are on the outer row. Even-numbered pins are on the inner row. The Hour register setting can be switched from 12hr format to 24hr format by clicking the -->24 button. RAM Screen The Single Read button reads the most recently selected RAM location. The Single Write button writes the most recently selected RAM location. The Burst Read button performs a Burst Read from the entire RAM. The Burst Write button performs a Burst Write to the RAM. Normally, all 31 locations are read, but the Burst Write length can be reduced. Burst Write always begins with RAM location 0. The Preset Data button performs a Burst Write to the RAM, setting all data to the same value (Figure 2). that the corresponding bit is a logic 1. The Read button updates the most recently selected Setup register’s checkboxes. The Write button writes the most recently selected Setup register (Figure 3). Auxiliary Functions 2-Wire Diagnostic The transition from evaluation to custom software development requires access to the low-level interface. Access the 2-wire diagnostic from the main screen’s View menu. The 2-wire Diagnostic screen allows you to send generalpurpose SMBus commands. The Hunt for active devices button scans the entire address space, reporting each address that is acknowledged. The two most-often-used protocols are SMBusReadByte and SMBusWriteByte. SMBusReadByte transmits the device address, a command or register select byte, then re-transmits the device address and reads 1 byte. SMBusWriteByte transmits the device address, a command or register select byte, and 1 byte of data (Figure 4). SPI/3-Wire Diagnostic The transition from evaluation to custom software development requires access to the low-level interface. Access the SPI/3-wire diagnostic from the main screen’s View menu. The SPI/3-Wire Diagnostic screen allows you to send SPI or 3-wire commands, or manipulate the parallel port pins directly. Each of the 25 pins is represented by a checkbox. A checkmark means that the corresponding pin is at a logic-high level. Pins that are inputs to the PC are grayed. The bit-banging SPI diagnostic transmits data using synchronous serial format (similar to Motorola’s 68HC11 SPI interface). The SPI interface sends and receives data simultaneously on separate pins. Parallel port pin 2 drives the clock, pin 1 drives DIN, pin 4 drives chip select, and pin 11 senses DOUT. Pins 2, 4, and 11 are inverted by open-collector drivers, while pin 1 drives DIN directly. The 3-wire interface uses a bidirectional data pin. The MAXSMBus board implements the 3-wire interface by using an open-collector driver. Pin 2 drives the clock, pin 3 drives data, pin 4 drives chip select, and pin 11 senses data. All these signals are inverted by the opencollector drivers. The least-significant bit (LSB) is transmitted first, and (CPOL = 1, CPHA = 0) mode is used (Figure 5). Setup Screen Each Setup register is represented by a group of eight checkboxes, one for each bit. A checkmark indicates _______________________________________________________________________________________ 3 Evaluates: MAX6900 Table 2. MAXSMBUS Connector Signals Evaluates: MAX6900 MAX6900 Evaluation System Figure 1. Main Screen Figure 2. RAM Screen Figure 3. Setup Screen 4 _______________________________________________________________________________________ MAX6900 Evaluation System Evaluates: MAX6900 Figure 4. 2-Wire Diagnostic Figure 5. SPI/3-Wire Diagnostic _______________________________________________________________________________________ 5 Evaluates: MAX6900 MAX6900 Evaluation System VL VCC VL 5 VL VCC R1 OPEN GND U2 4 SCL 1 I/O_VL IO_VCC 3 R2 OPEN SDA J1-15 J1-17 GND 4 3 Y1 Y2 MAX6900 1 2 3 C3 0.1µF 6 SDA 1 X1 2 2 4 IO_VCC I/O_VL 3 TO MAXSMBus BOARD VCC VCC SDA J1-4 J1-5 J1-13 VL X2 U1 J1-2 JU1 J1-6 J1-7 SCL VCC MAX3370 4 J1-1 J1-11 VCC U3 C4 0.1µF SDA 5 VL 5 J1-9 C1 0.1µF 2 VCC J1-3 JU2 MAX3370 SCL VCC R3 49.9kΩ 1 VL VL SCL J1-8 NC NC NC NC NC J1-19 J1-10 C5 10µF 10V C2 10µF 10V GND J1-12 J1-14 J1-16 J1-18 J1-20 NC Figure 6. MAX6900 EV Kit Schematic 6 _______________________________________________________________________________________ MAX6900 Evaluation Kit 1.0" Figure 7. MAX6900 EV Kit Component Placement Guide— Component Side Figure 8. MAX6900 EV Kit PC Board Layout—Component Side 1.0" Figure 9. MAX6900 EV Kit PC Board Layout—Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ______________________7 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. Evaluates: MAX6900 1.0"