Jason's Palm Computing Pages PCPD Serial Pin-Out Descriptions $Date: 1998/06/08 05:25:19 $

Note:

The following information was taken from the following images: http://www.palm.com/devzone/hdk/images/signals.gif
http://www.palm.com/devzone/hdk/images/cradle.gif
I've taken the information contained in these two images and coverted it to HTML so that all may benefit. While I have made a good effort to transcribe the information accurately, I AM NOT RESPONSIBLE FOR ANY ACTIONS YOU MAY TAKE BASED ON THE INFORMATION CONTAINED WITHIN.

Serial Interface Contacts

  PCPD (Rear View)               Cradle (Front View)

10 9 8 7 6 5 4 3 2 1             1 2 3 4 5 6 7 8 9 10
 | | | | | | | | | +->   DTR   <-+ | | | | | | | | | 
 | | | | | | | | +---> +3.3VDC <---+ | | | | | | | |
 | | | | | | | +----->   RD    <-----+ | | | | | | |
 | | | | | | +------->   RTS   <-------+ | | | | | |
 | | | | | +--------->   TD    <---------+ | | | | |
 | | | | +----------->   CTS   <-----------+ | | | |
 | | | +------------->  GPI 1  <-------------+ | | |
 | | +--------------->  GPI 2  <---------------+ | |
 | +----------------->  unused <-----------------+ |
 +------------------->   SG    <-------------------+

Palm Computing Platform Device (PCPD) Serial Connector Pin-out Description

The PCPD 10-pin edge connector has some EIA232-D (formerly RS232-C) interface signals and some additional signals to support the use of the HotSync cradle and the Palm Modem.

Pin #Signal Name (Direction)Function
1DTR (out) Non-standard implementation. Signal is named RS232_V+. This is the voltage doubler output from the RS232 transceiver's V+ pin (pin 3) through a 330 ohm resistor. It is used as the Data Terminal Ready (DTR) signal. When the serial port is "opened" by Serial Manager, it enables the RS232 transceiver and the UART. As long as the transceiver is enabled this pin outputs an asserted signal. The signal is 3.0 volts when the transceiver is shut down (normal mode) and is about 6.0 volts when the transceiver is enabled (HotSync). When this signal is at 6.0 volts it is a valid RS232 assertion.
Note: According to specifications, a 3.0 volt signal constitutes a valid RS232 assertion, but it "seems" as the time that all pocket modems which require DTR to be valid simply have a logic detector to detect the signal being greater than 4 volts. So, effectively 3 volts is not a valid assertion and that is why this simple implementation works.
2VCC (out) This is tied to Vcc (3.3v) through a 330 ohm resistor. This signal is connected to the HotSync button (normally open) on both the cradle and the Palm Modem. The other side of the HotSync button connects to pin 7 (GPI1).
3RD (in)Receive Data -- from PC to PCPD
4RTS (out)Request To Send -- hardware flow control handshake signal (from PCPD)
5TD (out)Transmit Data -- from PCPD to PC
6CTS (in)Clear To Send -- hardware flow control handshake signal (from PC)
7GPI1 (in)Interrupt line for initiating HotSync. This input requires a voltage greater than about 0.7 volts in order to turn on a MUN2214 NPN transistor which asserts a low on the DragonBall UART IRQ1 (U1 pin 38).
8GPI2Peripheral ID line (for HotSync). Signals "Modem HotSync" when asserted high (this is achieved in the Palm Modem because this pin is connected to pin2 through a 20K ohm resistor). This input requires a voltage greater than about 0.7 volts in order to turn on a MUN2214 NPN transistor which asserts a low on the DragonBall UART GPIO (U1 pin 32) to present a "modem connected" ID signal to the processor.
9Unused(Reserved)
10SGSignal ground.

Notes:

Palm/3COM 5-12-98
(minor modifications by Jason White)


Palm Cradle to DB-9F Serial Wiring Diagram

 PCPD/Cradle    DB-9F
 -----------    -----   
    (DTR) 1 ----- 6 (DSR)
(+3.3VDC) 2 ---------------+
     (RD) 3 ----- 3 (TD)   |
    (RTS) 4 ----- 8 (CTS)  o|_ HotSync
     (TD) 5 ----- 2 (RD)   o|  Button
    (CTS) 6 ----- 7 (RTS)  |
   (GPI1) 7 ---------------+
   (GPI2) 8 Unused
          9 Unused
    (SG) 10 ----- 5 (SG)

Jason's Palm Computing Pages PCPD Serial Pin-Out Descriptions $Date: 1998/06/08 05:25:19 $