Registered: Oct 1999
Location: Cincinnati, OH
Posts: 109

Handspring sells both USB and Serial Visors. However, how does one device do both? Does the Visor itself contain the circuitry to handle both connection types or does the Visor only handle USB and the serial cradle mangles the connectiont o serial through buffers, etc.?

Registered: Mar 2000
Location: Roseville, MN, USA
Posts: 161

The Visor is a USB device. The serial cradle handles the conversion of serial to USB (basically).

Registered: Dec 1999
Location: Connecticut USA
Posts: 2682

Just for clarifcation, the cradle does not convert USB to serial or vice versa.

Actually, the Visor handles both USB and serial independently. The docking connector has signal lines for both interfaces. The cradle actually determines the difference.

The USB cradle is pretty straight forward. Connect it to a working USB port and the Visor is happy (usually ).

The serial cradle does a "trick" or two to tell the Visor it's connected serially. Basically this is done by having pin 2 on the serial cradle tied to ground (the same scenario for communicating with a keyboard). This tells the Visor that it will sync on the serial lines instead of the USB ones.

The serial cradle also contains a transceiver circuit to convert the Visor's TTL-level signals to the PC's RS232-level. This is part of the reason legacy serial devices that work with the Palm's don't work with the Visor. Also, the Visor serial interface only contains RXD and TXD signals. There are NO handshaking line at all.



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MarkEagle - Ice is nice!

Registered: Oct 1999
Location: Cincinnati, OH
Posts: 109

I guess my goal was to determine how realistic it would be to build my own serial cable for my USB Visor (to then connect to the serial->Qualcomm connector for my cell phone, etc.)

If the Visor is not outputting the level of signal for required for normal serial devices (i.e. the serial interface of a cell phone), then some extra circuitry would be required rather than just straight wires.

Thanks for the input.

Registered: Dec 1999
Location: Connecticut USA
Posts: 2682

Unfortunately, a "simple" cable isn't possible. There was a very good discussion about this a while back... check out this thread.

I have built 3 of my own serial cables using the information above. They work GREAT for syncing but I have been unsuccessful at using any other external peripherals. This has to do with the lack of handshaking lines.

On a hardware level, this is one of the significant differences between the Visor and a Palm device. I believe Handspring's intent was for peripherals to be Springboard modules (makes sense to me given the wide open possibilities of the Springboard).

I don't think you'll have any luck connecting to your phone from the Visor's docking connector...

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MarkEagle - Ice is nice!

Registered: Oct 1999
Location: Cincinnati, OH
Posts: 109

Hmmm... Sounds like maybe we need an RS232 SpringBoard. Would anyone else be interested in something like this? What would be a good price point?

Registered: Dec 1999
Location: Connecticut USA
Posts: 2682

An RS232 Springboard might make sense IF it were very inexpensive (I'd say no more than $30.00, if that's possible). The diagnostic module from EFIG has an RS232 port but i don't know anymore about it.

As far as I'm concerned, the SixPak module (if it ever comes to be!) is all I'll probably need (today, that is ). But who knows what the future holds?

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MarkEagle - Ice is nice!

Registered: Apr 2000
Location:
Posts: 73

The EFIG diagnostics card with RS232 port (although expensive) works flawlessly with my Visor. I connect it to my Qualcomm Touchpoint cellphone (Sprint PCS)using the Sprint Data Connectivety Kit cable (expensive) and a null Modem. My Visor Modem Preference menu is set up as follows:

modem=standard
speed=19,200
spkr=low
flow control=automatic
country=other
string=AT&FX4

The Communication Menu of the EFIG is :

Port=built-in
baud=19200
Handshake=hardware
parity=none
stop bits=1
data bits=8

I have Eudora for palm and I have Proxiweb. I download my email (amazingly quick) and I even surf the web. Most amazingly, I have my corporate email (Lotus Notes) forwarded to my POP email account and I can download my email onto my Visor at any time from anywhere Sprint has coverage. I attend a lot of boring meetings and it blows people away when I can get my emails on my Visor in real time. I'm ahead of the game. I can respond instantly. I don't need my laptop now when I travel!

Registered: Jan 2000
Location: Brisbane, Australia
Posts: 22

Does anyone know the details of how the visor handles USB at the cpu level? I know the Dragonball can manage serial, but as for USB it doesnt seem to (from the info i can find).

Which would mean, to create an applaction which makes bare access to the usb port would requre a *lot* of tricky code

The other posibility that comes to mind is that the visor might spit out standard serial through the dragonball's SPI and then convert this into a USB signal through extra hardware (I believe this is possible?). Sorry, I understand the software side, but havent a clue when it comes to the electronics

I have a very interesting project that I am beginning In order to complete it I need to gain access to the USB interface without using the PalmOs at all. So I'm hoping the second case is how it works (SPI to usb through hardware). That would make things quite easy, if not, well then there is a bit of trouble

If anyone has any knowledge of this or any ideas, please let me know.

Registered: Dec 1999
Location: Connecticut USA
Posts: 2682

quote:

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Originally posted by nashdj:
Does anyone know the details of how the visor handles USB at the cpu level?

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I'll admit I probably know less about USB at the hardware level than you...

The HS Develeper Kit manual says that the Visor is a USB "slave" device:

quote:

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The Cradle Connector contains two serial buses that communicate with external devices: a USB
bus and a simple serial bus. The high-speed USB interface is a slave-only interface, providing a payload bandwidth of up to 400 Kbps between a host PC or Mac and the handheld device. The serial port provides asynchronous capability to low-speed devices (9600 Kbps or less).

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I think this means that it can "talk" to a USB host but cannot serve as one, meaning USB peripherals cannot be attached to the Visor. Also, the USB spec contains stringent power specs that the Visor simply cannot supply.

If I had to guess, I'd say your second case above would be correct, but it's just a guess.

I've made a few inquiries to HS DevSupport regard the serial interface but still haven't heard back from them. If and when I do, I'll ask about this USB stuff as well.

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MarkEagle - Ice is nice!

Registered: Jan 2000
Location:
Posts: 391

quote:

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Originally posted by MarkEagle:
I have built 3 of my own serial cables using the information above. They work GREAT for syncing but I have been unsuccessful at using any other external peripherals. This has to do with the lack of handshaking lines.

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Registered: Dec 1999
Location: Connecticut USA
Posts: 2682

In my very informal testing, I've discovered that, for example, if you try to dial a connection using the Modem panel in Prefs, no activity occurs at the RXD or TXD lines of the connector. This leads me to believe that internally, the Visor is routing normal serial to the Springboard (where it expects a modem to be). Additionally, the DevKit manual explains that when the Visor detects a "serial" connection on the docking connector, it wants incoming data to be in the form of RemoteUI packets (specifically it mentions keyboard interfacing). What confuses me is that serial syncing works... does that mean serial sync data is in the form of RemoteUI packets? Another of my as yet unanswered questions.

Your comment about power is also probably true as most peripherals don't generate the power needed to supply the transceiver circuit (a minimum of 5 volts in the case of the design I used).

Again, I've asked HS for some clarification in this are but as of yet haven't heard from them.

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MarkEagle - Ice is nice!

Registered: Jan 2000
Location: Brisbane, Australia
Posts: 22

markeagle,
Well I was going to try mailing them, but I figured it would take a while.

Slave or not doesnt matter to me. I just need to be able to spit data between the visor and computer. At an assembly code level.

I'm mad hehehe.. I have this huge project which I'm keeping secret until, well until it works. I just want to see if I can do it myself before someone beats me to it. One or two weeks and I'll release the first stage, but I doubt to have the usb problem sovled by then. I'm mad ahhaha

(sorry dont mind me )

Registered: Jan 2000
Location:
Posts: 391

I was able to get the Visor to talk to the PC through a terminal program through the cradle. No luck with modems, as I said... they don't seem to deliver the juice.

After I get some pesky real-life issues out of the way I'm going to give it a shot with a battery-powered cable adapter.