Use a DS3900 to Evaluate I&sup
use a ds3900 to evaluate i²c-compatible devices for successful bidirectional communication
abstract: this application note explains the design considerations and hardware requirements for developing a hardware solution to establish i²c-compatible communications using a ds3900.
introduction the ds3900 is used to evaluate i²c-compatible components, and it provides fast, bidirectional communication with 2-wire devices using a pc's serial port. figure 1 shows the recommended configuration for establishing communications between a ds3900 and an i²c-compatible device. an example of a breakout board for the ds3900 is shown in figure 2. this small, efficient pcb (printed circuit board) provides everything necessary for i²c communications with the ds3900, and it allows the user to quickly interface with i²c-compatible devices.
figure 1. typical ds3900 interface schematic.
figure 2. example ds3900 interface board.
there are several notable aspects of the interface which users need to understand. all optional and critical functions of the circuit are detailed below.
power-supply considerations ideally, the ds3900 should be powered by the same supply as the dut (device under test). by using the same supply for the dut and the ds3900, the pullup resistors can be tied directly to vcc. a single decoupling capacitor from vcc to gnd will suffice in most applications. however, the rs-232 transceiver used on the ds3900 can inject noise on the vcc and gnd signals. this noise is significantly reduced when a 47µf tantalum capacitor¹ is also used to decouple the supply. the three ds3900 ground pins must all be connected to ground. all other unused i/o and the active-low mclr pins should be left electrically unconnected.
pullup resistor considerations the ds3900 can use either the on-board pullup resistors for sda (serial data) and scl (serial clock), or the resistors already employed in an existing application. the switch² in figure 1 controls whether or not the ds3900's on-board resistors are used for the pullup to vcc. in short, if the ds3900 is to be used on an i²c bus that already has pullup resistors, use the switch to disconnect the ds3900's on-board pullup resistors. sda and scl can then be attached safely to the target board or component.
hardware considerations the ds3900 has a number of convenient features. p3 is an open-collector i/o that can be used to drive a status led. the connection in figure 1 is made through vcc, which will affect power-supply currents when the led is turned on. there are several other i/o pins available on the ds3900; their functions are defined in the ds3900 data sheet.
communicating with the ds3900 the communications with the ds3900 are handled by either the ds3900 ev kit or the i²c-specific software included with the maxim device being evaluated. if no device-specific software exists, the ds3900 ev kit software will be more than sufficient. the ds3900 connects to a pc through the rs-232 port. the evaluation software kits available on the ftp site are all executables with intuitive user interfaces.
conclusion things to remember:
use the same supply for the ds3900 and the dut if at all possible. use additional decoupling in applications sensitive to supply and gnd noise. make sure that the sda and scl pullup resistors are used either on the ds3900 or on the target board. make sure that all three (3) gnd pins of the ds3900 are grounded and connected to the gnd reference of the target board. if the preceding recommendations are followed, it will be easy to use the ds3900 to evaluate i²c-compatible devices.
notes
¹digikey® offers the 47µf capacitor used for ds3900 evaluation of analog signals. here the avx® pn# is used. any equivalent capacitor will suffice.
²the dpdt (dual position, double throw) dip switch on ds3900 controls pullup resistors.
avx is a registered trademark of avx corporation.
digi-key is a registered trademark of digi-key corporation.
特斯拉无人驾驶中国首撞！无视障碍物加速
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Use a DS3900 to Evaluate I&sup
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网速到底能多快
abstract: this application note explains the design considerations and hardware requirements for developing a hardware solution to establish i²c-compatible communications using a ds3900.
introduction the ds3900 is used to evaluate i²c-compatible components, and it provides fast, bidirectional communication with 2-wire devices using a pc's serial port. figure 1 shows the recommended configuration for establishing communications between a ds3900 and an i²c-compatible device. an example of a breakout board for the ds3900 is shown in figure 2. this small, efficient pcb (printed circuit board) provides everything necessary for i²c communications with the ds3900, and it allows the user to quickly interface with i²c-compatible devices.
figure 1. typical ds3900 interface schematic.
figure 2. example ds3900 interface board.
there are several notable aspects of the interface which users need to understand. all optional and critical functions of the circuit are detailed below.
power-supply considerations ideally, the ds3900 should be powered by the same supply as the dut (device under test). by using the same supply for the dut and the ds3900, the pullup resistors can be tied directly to vcc. a single decoupling capacitor from vcc to gnd will suffice in most applications. however, the rs-232 transceiver used on the ds3900 can inject noise on the vcc and gnd signals. this noise is significantly reduced when a 47µf tantalum capacitor¹ is also used to decouple the supply. the three ds3900 ground pins must all be connected to ground. all other unused i/o and the active-low mclr pins should be left electrically unconnected.
pullup resistor considerations the ds3900 can use either the on-board pullup resistors for sda (serial data) and scl (serial clock), or the resistors already employed in an existing application. the switch² in figure 1 controls whether or not the ds3900's on-board resistors are used for the pullup to vcc. in short, if the ds3900 is to be used on an i²c bus that already has pullup resistors, use the switch to disconnect the ds3900's on-board pullup resistors. sda and scl can then be attached safely to the target board or component.
hardware considerations the ds3900 has a number of convenient features. p3 is an open-collector i/o that can be used to drive a status led. the connection in figure 1 is made through vcc, which will affect power-supply currents when the led is turned on. there are several other i/o pins available on the ds3900; their functions are defined in the ds3900 data sheet.
communicating with the ds3900 the communications with the ds3900 are handled by either the ds3900 ev kit or the i²c-specific software included with the maxim device being evaluated. if no device-specific software exists, the ds3900 ev kit software will be more than sufficient. the ds3900 connects to a pc through the rs-232 port. the evaluation software kits available on the ftp site are all executables with intuitive user interfaces.
conclusion things to remember:
use the same supply for the ds3900 and the dut if at all possible. use additional decoupling in applications sensitive to supply and gnd noise. make sure that the sda and scl pullup resistors are used either on the ds3900 or on the target board. make sure that all three (3) gnd pins of the ds3900 are grounded and connected to the gnd reference of the target board. if the preceding recommendations are followed, it will be easy to use the ds3900 to evaluate i²c-compatible devices.
notes
¹digikey® offers the 47µf capacitor used for ds3900 evaluation of analog signals. here the avx® pn# is used. any equivalent capacitor will suffice.
²the dpdt (dual position, double throw) dip switch on ds3900 controls pullup resistors.
avx is a registered trademark of avx corporation.
digi-key is a registered trademark of digi-key corporation.
特斯拉无人驾驶中国首撞！无视障碍物加速
特斯拉电池供应商松下2-3年内将实现电池无钴化
主机开了电脑屏幕不亮是什么原因？
HTC U最新消息：新旗舰渲染图曝光：支持边框触控
昭和壳牌太阳能展出第2代CIGS太阳能电池面板
Use a DS3900 to Evaluate I&sup
微雪电子SG90舵机简介
芯片静态功耗是什么？如何产生？ATECLOUD-IC芯片测试系统如何测试？
中国移动以“全千兆”为引领，发布了智慧家庭“四新”策略
如何大幅提高物联网器件的电池能效比
安机械研制翻桩器 已投入现场使用
运放基础知识
p型mos管导通条件
LCD和相机总线方案中的功率转折点
深度学习NLP领军人Chris Manning教授将接替李飞飞出任斯坦福人工智能实验室负责人
Vishay推出厚膜功率电阻器，可选配NTC热敏电阻和PC-TIM简化设计，节省电路板空间并降低成本
音频放大器不再与FM功能水火不容
农民工减少近300万 工业机器人负增长
Silicon Labs展示高级计量无线解决方案
网速到底能多快