j****9
发帖数: 2295 | 1 You have been tasked with developing an embedded device responsible for:
- driving a small touch screen
- collecting user input (in the form of buttons and dials)
- displaying system status (through the screen and through LED indicators)
- collecting data from up to four serial ports
- relaying all this information to a x86 system and receiving additional
indicator information from the x86 system
Question 2A:
Architecturally, how would you connect the embedded device to the x86 system
and why? (The x86 has Ethernet, USB, RS-232, and Bluetooth. It is in close
physical proximity to the embedded device and shares the same power source.）
不是很确定。想听听大家想法。 |
b*******r
发帖数: 1130 | 2 感觉至少需要一定的power去驱动Touch Screen，还需要双向通信
网线估计没power，bluetooth可能power不够，USB应该没问题，RS-232也提供power，
但voltage level可能过高。 |
j****9
发帖数: 2295 | 3 shares the same power source 怎么理解。 |
j****9
发帖数: 2295 | 4 为啥RS232的voltage level过高？
【在 b*******r 的大作中提到】
: 感觉至少需要一定的power去驱动Touch Screen，还需要双向通信
: 网线估计没power，bluetooth可能power不够，USB应该没问题，RS-232也提供power，
: 但voltage level可能过高。
|
l***g
发帖数: 1035 | 5 很少有embedded chip 会有多于4个uart. X86那个也是uart不是rs232, ，which
requires tranceiver.
I would say uart if there is spare channel since they share the same power
thus same signal level.
Most likely the data is not that much and the two devices are close.
Other options are overkill though they would work.
indicators)
additional
system
close
【在 j****9 的大作中提到】
: You have been tasked with developing an embedded device responsible for:
: - driving a small touch screen
: - collecting user input (in the form of buttons and dials)
: - displaying system status (through the screen and through LED indicators)
: - collecting data from up to four serial ports
: - relaying all this information to a x86 system and receiving additional
: indicator information from the x86 system
: Question 2A:
: Architecturally, how would you connect the embedded device to the x86 system
: and why? (The x86 has Ethernet, USB, RS-232, and Bluetooth. It is in close
|
l***g
发帖数: 1035 | 6 题出的挺烂的。
indicators)
additional
system
close
【在 j****9 的大作中提到】
: You have been tasked with developing an embedded device responsible for:
: - driving a small touch screen
: - collecting user input (in the form of buttons and dials)
: - displaying system status (through the screen and through LED indicators)
: - collecting data from up to four serial ports
: - relaying all this information to a x86 system and receiving additional
: indicator information from the x86 system
: Question 2A:
: Architecturally, how would you connect the embedded device to the x86 system
: and why? (The x86 has Ethernet, USB, RS-232, and Bluetooth. It is in close
|
g******u
发帖数: 3060 | 7 close proximity - then kick away Ethernet and Bluetooth.
USB is overkill for this job.
so RS232 is the only thing left.
although I'd use a I2C or LIN. |
l***g
发帖数: 1035 | 8 所以说题出的不好，在一个板子上也是close， 在一个机箱也是，在一个屋子也可以。
x86可以是芯片也可以是计算机，一个电源可以是一个110v也可以是一个12V 也可以是
一个5V。
【在 g******u 的大作中提到】
: close proximity - then kick away Ethernet and Bluetooth.
: USB is overkill for this job.
: so RS232 is the only thing left.
: although I'd use a I2C or LIN.
|
j****9
发帖数: 2295 | 9 我觉的出题人是指x86为计算机。相同的电源指的是110v。 |
i*****t
发帖数: 24265 | 10 俺的答案是USB
1 x86的usb供电足够给小触摸屏和串口等，无需外接电源
2 usb通讯速度足够同时传输4个115k串口采集的数据到x86 pc
其他的ethernet，232蓝牙啥的电源不行，速度也不匹配
indicators)
additional
system
close
【在 j****9 的大作中提到】
: You have been tasked with developing an embedded device responsible for:
: - driving a small touch screen
: - collecting user input (in the form of buttons and dials)
: - displaying system status (through the screen and through LED indicators)
: - collecting data from up to four serial ports
: - relaying all this information to a x86 system and receiving additional
: indicator information from the x86 system
: Question 2A:
: Architecturally, how would you connect the embedded device to the x86 system
: and why? (The x86 has Ethernet, USB, RS-232, and Bluetooth. It is in close
|
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i*****t
发帖数: 24265 | 11 是说嵌入式设备跟主机距离很近，直接享用x86主机的接口的电源无需外接电源
usb这点很符合
【在 j****9 的大作中提到】
: shares the same power source 怎么理解。
|
i*****t
发帖数: 24265 | 12 +-9V，主要是电流太小无法带动触摸屏，另外串口速度太慢，4个embed采集串口的数据
无法用1个串口传送到x86主机，除非用x86的高速串口外加usb电源，需要额外的板卡，
还不如直接用usb口供电+通讯完事
【在 j****9 的大作中提到】
: 为啥RS232的voltage level过高？
|
j****9
发帖数: 2295 | 13 恩。
【在 i*****t 的大作中提到】
: +-9V，主要是电流太小无法带动触摸屏，另外串口速度太慢，4个embed采集串口的数据
: 无法用1个串口传送到x86主机，除非用x86的高速串口外加usb电源，需要额外的板卡，
: 还不如直接用usb口供电+通讯完事
|
l***g
发帖数: 1035 | 14 如果说是计算机就没必要说x86. 一个屋子都是同一个110v, 也没意义说。出题的人脑
子里已经有了这个系统但没说清楚。
【在 j****9 的大作中提到】
: 我觉的出题人是指x86为计算机。相同的电源指的是110v。
|
l***g
发帖数: 1035 | 15 Usb只有5伏0.5-1安培，给数据采集加触摸屏肯定不够。4个串口数据当然可以echo到第
五个串口。
【在 i*****t 的大作中提到】
: +-9V，主要是电流太小无法带动触摸屏，另外串口速度太慢，4个embed采集串口的数据
: 无法用1个串口传送到x86主机，除非用x86的高速串口外加usb电源，需要额外的板卡，
: 还不如直接用usb口供电+通讯完事
|
i*****t
发帖数: 24265 | 16 呵呵，没有马达的话，500mA电流足够啦，就算带动个普通的小平板电脑都够。
另外4个串口全双工115200bps的话，用x86标准的115k的串口无法copy所有4个口的数据
，所以pc需要额外加高速串口版块。俺以前就开发过微处理器模拟4个串口链接不同传
感器，然后数据实时上传到pc，当时pc用的高速串口才行，否则只有减低采集速率啦。
【在 l***g 的大作中提到】
: Usb只有5伏0.5-1安培，给数据采集加触摸屏肯定不够。4个串口数据当然可以echo到第
: 五个串口。
|
d******d
发帖数: 2210 | 17 题目是出得挺烂的，很多含糊的地方。当然面试时候可以互相沟通把条件搞清楚。
我对 最后一句share power 的理解是 power 从x86那边来，同一个power module.
power consumption 就不必考虑了。
Ethernet 总是先出局的。
indicators)
additional
system
close
【在 j****9 的大作中提到】
: You have been tasked with developing an embedded device responsible for:
: - driving a small touch screen
: - collecting user input (in the form of buttons and dials)
: - displaying system status (through the screen and through LED indicators)
: - collecting data from up to four serial ports
: - relaying all this information to a x86 system and receiving additional
: indicator information from the x86 system
: Question 2A:
: Architecturally, how would you connect the embedded device to the x86 system
: and why? (The x86 has Ethernet, USB, RS-232, and Bluetooth. It is in close
|
b*******d
发帖数: 239 | 18 support this。
【在 i*****t 的大作中提到】
: 俺的答案是USB
: 1 x86的usb供电足够给小触摸屏和串口等，无需外接电源
: 2 usb通讯速度足够同时传输4个115k串口采集的数据到x86 pc
: 其他的ethernet，232蓝牙啥的电源不行，速度也不匹配
:
: indicators)
: additional
: system
: close
|
