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Why would you need two USB ports?
Are you connecting your device to two computers at the same time?
If you are thinking of plugging USB devices into your project and relaying the information to the ethernet adapter ... you can't do it with the on-board USB peripheral.
PIC chips don't do USB "Host" mode. At least not the PIC's that PBP can work with.
I think your best bet is the VNC2 - Vinculum-II Programmable USB 2.0 Host
DT
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Re: How to support two (dual) USB ports?
Darrel, maybe a more detailed explanation of the application is needed in hopes you can advise me of my best options.Originally Posted by Darrel Taylor
The client is using temperature sensors as described at this website: http://www.vfcdataloggers.com/usbtcdatalogger.aspx As you can see each temperture monitoring unit is also a data logger and has a USB port that is used to access the stored data on the device. He wants me to provide a wireless gateway so that the temperature readings on these devices can be transmitted via WiFi to internet and displayed on a web page. He wants my embedded wireless controller to interface simultaneously with both of the temperature monitor devices to monitor two temperature probes at two different locations in a refrigerator....the freezer and the refrigeration compartment.
Therefore, my embedded controller has to have two USB ports and be able to dowload the temperature data from both temperature monitors on an hourly basis when an alarm interrupt is received from a RTC that will be in the embedded controller. The temperature probes will be continuously plugged into the controller via thetwo USB interfaces but will only download when qued to do so by the controller. The PIC microcontrollers (plural assuming one will be required for each USB Port) will(each download the hourly temperature reading from their respective thermometer that is plugged in to its USB port. One of the two pics will also be interfaced to the RTC and to the WiFi module as well as its thermometer/USB port. This "master" PIC will monitor the alarm interrupt from the RTC and upon receipt of an hourly alarm interrupt will start the data loggin/reporting process. The other PIC must send the measurement that is downloaded from its thermometer/USB port to the other PIC (serial?), which will then send both temperature readings to the WiFi module for reporting over the internet to the website.
With this kind of a configuration can't I program each of the PICs with PBP to download the temperature readings from their respective USB ports without having a "Host Mode"?
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Re: How to support two (dual) USB ports?
USB requires a host. The PIC using the on-board USB or a USART to USB interface, and your temperature sensors are not capable of doing this. The VNC2 that Darrel linked to looks like it might work for your application though.
They even have precompiled rom's available. This one looks like it will do what you need, it is a USB host bridged to a UART port.
http://www.ftdichip.com/Support/Docu...ost_Bridge.pdf
Last edited by spcw1234; - 18th January 2012 at 00:59.
Shawn
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Re: How to support two (dual) USB ports?
Shawn, I really appreciate your and Darrel's input on this. I reviewed the websites you both pointed to and have some questions.
1) I presume that in my application, the temperature datalogger becomes the USB host and my 18F2550 becomes the slave with a UART that is bridged to by the VNC chip...is that correct??
2) Since my application has to provide an interupt to the temperature datalogger when it wants the latest temperature sent via the USB to my application, how can I get the interrupt to the datalogger....it appears that the total interface using the UART<---VNC<---->USB Host is only uni-directional between the UART and VNC and would prevent me from sending the interrupt to the USB Host via the VNC. Don't quite understand how I am going to handle that if I use VNC. Can you elaborate??
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