In-circuit programming switch
a simple bidirectional analog switch (max4525) facilitates in-circuit programming by providing dual service for two lines (sda and scl) on the programmable device: for normal operation they connect to other circuitry, and for programming mode they connect to the programming header.
a similar version of this article appeared in the october 21, 2008 issue of ed magazine.
many devices now available require programming through a serial bus such as i²c. this programming can be done during final test, after the circuit board has been assembled. in many cases the pins used for programming are used for something else during normal operation, and the bus itself can also be used for another function during normal operation.
a simple analog multiplexer circuit facilitates the in-circuit programming (figure 1). the multiplexer shown is a bidirectional analog switch (max4525). during normal operation, its input is pulled to ground by r1, causing the serial lines to connect to the rest of the circuit. during programming mode, the programming header asserts a logic high on the pin connected to the multiplexer input, causing the mux to switch over to the pins on the programming header.
figure 1. this analog switch (max4525) enables in-circuit programming by providing dual service for two lines (sda and scl) on the programmable device: for normal operation they connect to other circuitry, and for programming mode they connect to the programming header.
an i²c bus is present in the figure, so pullup resistors are provided for other circuitry on the board. the device programmer that connects to the programming header must have its own pullup resistors. the series resistance added by the multiplexer should be accounted for by other circuitry on the board. to avoid forward-biasing the esd diodes, the serial data lines should not go below ground or above the vcc voltage of the max4525.
“核武狂魔、两弹元勋”英伟达（NVIDIA）教主黄仁勋的百亿美元豪赌赢了！
智慧交通什么时候可以全方位的发挥作用
ch32控制板是什么？
国内工业机器人产量迎来开门红未来产量增长仍将持续
库存多！HP11731A衰减器
In-circuit programming switch
全球智能手机市场已经保持固化，芯片市场面临着洗牌
三星下半年将会发布拥有旗舰级性能的Exynos 1080芯片
4×4键盘模块电路图
微软宣布将于2020年推出Edge浏览器Linux版本
苹果决定彻底抛弃这款手机了
华为mate10就要来了！华为mate9降至冰点价，对比华为P10，你选择谁？
浩瀚卓越618预售，超值惊喜价就把新款稳定器带回家
怎么测整流桥的好坏？
基于数字锁相环实现X光安检机控制信号时钟提取系统的设计
视觉检测技术在电子元器件中外观缺陷检测中的应用
iPhone 7价格再次下跌，已破三千
Dialog汽车级PMIC产品组合
什么是KC认证 锂电池做KC认证
谷歌加强了无人驾驶汽车辨别儿童的能力
a similar version of this article appeared in the october 21, 2008 issue of ed magazine.
many devices now available require programming through a serial bus such as i²c. this programming can be done during final test, after the circuit board has been assembled. in many cases the pins used for programming are used for something else during normal operation, and the bus itself can also be used for another function during normal operation.
a simple analog multiplexer circuit facilitates the in-circuit programming (figure 1). the multiplexer shown is a bidirectional analog switch (max4525). during normal operation, its input is pulled to ground by r1, causing the serial lines to connect to the rest of the circuit. during programming mode, the programming header asserts a logic high on the pin connected to the multiplexer input, causing the mux to switch over to the pins on the programming header.
figure 1. this analog switch (max4525) enables in-circuit programming by providing dual service for two lines (sda and scl) on the programmable device: for normal operation they connect to other circuitry, and for programming mode they connect to the programming header.
an i²c bus is present in the figure, so pullup resistors are provided for other circuitry on the board. the device programmer that connects to the programming header must have its own pullup resistors. the series resistance added by the multiplexer should be accounted for by other circuitry on the board. to avoid forward-biasing the esd diodes, the serial data lines should not go below ground or above the vcc voltage of the max4525.
“核武狂魔、两弹元勋”英伟达（NVIDIA）教主黄仁勋的百亿美元豪赌赢了！
智慧交通什么时候可以全方位的发挥作用
ch32控制板是什么？
国内工业机器人产量迎来开门红未来产量增长仍将持续
库存多！HP11731A衰减器
In-circuit programming switch
全球智能手机市场已经保持固化，芯片市场面临着洗牌
三星下半年将会发布拥有旗舰级性能的Exynos 1080芯片
4×4键盘模块电路图
微软宣布将于2020年推出Edge浏览器Linux版本
苹果决定彻底抛弃这款手机了
华为mate10就要来了！华为mate9降至冰点价，对比华为P10，你选择谁？
浩瀚卓越618预售，超值惊喜价就把新款稳定器带回家
怎么测整流桥的好坏？
基于数字锁相环实现X光安检机控制信号时钟提取系统的设计
视觉检测技术在电子元器件中外观缺陷检测中的应用
iPhone 7价格再次下跌，已破三千
Dialog汽车级PMIC产品组合
什么是KC认证 锂电池做KC认证
谷歌加强了无人驾驶汽车辨别儿童的能力