Newton Interconnect Port
Hardware Specification for the MessagePad


Draft Preliminary, Confidential. © 1997 Apple Computer, Inc. 5/23/97




This document describes the Newton Interconnect Port. This port was designed to connect the MessagePad to a a variety of peripherals and devices, such as: a simple AppleTalk serial cable connection, a wireless communications device connection port, and a complex docking port for a desktop dock that provides audio I/O capabilities.

Because of the wide array of devices that may be connected to the MessagePad, the Newton Interconnect Port has been designed with the flexibility needed to accommodate the majority of such devices. There is no minimum set of required signals: a device could, for example, use only audio out to provide a connection to a set of amplified speakers.

The Newton Interconnect Port contains the following groups of pins:


Overview of the Serial Channels

The Newton Interconnect Port provides two serial channels - 0 and 3. Channel 0 has a LTC1323 line driver connected to the Newton Interconnect Port, and can be used as either a serial channel or as a differential AppleTalk connection. Channel 3 can also be used with a serial port, but has no line driver, so developers will probably need to provide one.

A block diagram of the Newton Interconnect Port, and its channels, is shown in Figure 1-1.


Figure 1-1 Serial Ports and Enables


Serial Channel 0
(CMOS Levels) RS-422 levels
Digital <-----------------> LTC1323 Line Driver <-----------------> Newton
Controller <------------------ ------------------------- -------------------> Interconnect ----->
Serial Channel 3
(CMOS Levels)



Serial Channel 0

The LTC1323 Line Driver, connecting Serial Channel 0 to the Newton Interconnect Port, provides RS-422 level inputs and outputs. Channel 0 provides a differential pair for Receive Data (RXD+/-) and Transmit Data (TXD+/-), as well as a pair of hardware handshake signals (HSKi and HSKo). There is also a General-Purpose I/O line (GPI) that can be used as a ring indicator.


Modes Supported

Channel 0 supports the following modes:

Asynchronous Capabilities

Channel 0 supports the following asynchronous capabilities: The line driver is enabled internally by the MessagePad via a General-Purpose I/O (GPIO) pin. When this I/O pin is not enabled, the LTC 1323 Line Driver is in shutdown mode and will not drive the internal serial bus. The Newton OS is configured to enable the 5V power supply whenever Serial Port 0 is selected.


Connection to a Standard Apple Serial Cable

Figure 1-2 shows the connections that convert the Newton Interconnect Port to a standard Apple Serial Connection. The figure shows a male DIN 8 connector and the Newton Interconnect Port. Both connectors are shown as they appear to the corresponding connectors on the peripheral.

Figure 1-2 Din 8 Connection to Newton Interconnect Serial Port 0
(Original drawing showed lines between pin connections)

DIN 8
8--7--6
5--4--3
2--1

Interconnect
13-12-11-10--9--8--7--6--5--4--3--2--1
26-25-24-23-22-21-20-19-18-17-16-15-14


Table 1-1 Din 8 Connection to Newton Interconnect Serial Port 0

Signal Name Newton Interconnect Pin DIN 8 Pin
HSKo 19 1
HSKi 20 2
TXD- 18 3
Gnd 23 4
RXD- 8 5
TXD+ 6 6
GPI 7 7
RXD+ 21 8


Accessing Serial Channel 0

Serial Channel 0 can be accessed through communication endpoints using the standard Newton Serial Tool, AppleTalk Tool and Modem Tool. This section assumes that you are already familiar with the Newton Operating System's communication architecture. See the book Newton Programmer's Guide: Communications for an explanation of how to access Serial Channel 0.


Serial Channel 3

Serial Channel 3 is connected directly to the Newton Interconnect Port. Because the channel is always enabled, care must be taken in its use. The Serial Channel 3 signals are intended to be used with an external, serial line driver, such as an LTC1323. The LTC1323 inverts some of the signals, so if a peripheral will be connected directly to the Interconnect Port, invertors may be required to maintain the correct signal polarity.

Accessing Serial Channel 3

Serial Channel 3 can be accessed through communication endpoints using the standard Newton Serial Tool, AppleTalk Tool and Modem Tool. This section assumes that you are already familiar with the Newton Operating System's communication architecture. See the Newton Programmer's Guide: Communications for an explanation of how to access Channel 3.

Audio

The Newton Interconnect Port has both Audio Out and Audio In capabilities. These can be used to connect to auxiliary audio devices.

AudioOut is a single-ended signal at line level, referenced from AGND. AudioOut is capable of driving impedance loads down to 1K Ohm. The Analog Controller output's audio to either the internal speaker, the AuxAudioOut pin, or both. See Table 1-2 for the output audio parameters.


Table 1-2 Audio Out Specification Parameters

Parameter Min Typical Max
Full Scale Output Voltage 0.85 V peak 1.0 V peak 1.15 V peak
Instantaneous Dynamic Range (Attenuation at 0dB) 65 dB 68 dB ---
Frequency Response (7.2 kHz Word Rate) -0.6dB --- 0.6dB
Frequency Response (21.6 kHz Word Rate) -0.8dB --- 0.6dB
Programmable Output Level Attenuation -102.4dB --- 0dB
Gain Step Size -- 2.49dB ---
Gain Drift --- 3.50ppm/C ---
Common Mode Output Voltage --- 1.0V ---
Output Impedance --- 10W ---
Load Impedance 1kW --- ---
Short Circuit Current Limit --- --- 50mA
Total Harmonic Distortion at -0.5 dB Full-Scale Level --- 0.05% 0.07%
AudioIn is a single-ended signal at line level, referenced from AGND. The Analog Controller can accept input from either the internal microphone or the Newton Interconnect Port.

Audio In Specification to be supplied



Dock Attached

The Newton Interconnect Port provides a single control signal, prodDockAttach, that can be used to perform two functions: wake the system from the Sleep state, or allow the MessagePad to detect the presence of a dock and perform autodocking connection functions with a desktop machine. prodDockAttach is a General-Purpose I/O (GPIO) signal that the MessagePad configures as an active-low input.

Waking the System

If the MessagePad is in the Sleep state, it can be awakened by pulsing the prodDockAttach signal low for approximately 1msec. prodDockAttach must conform to the 3.3V CMOS voltage levels for logical high and low. This signal is normally held at a CMOS-level logical high by a pullup resistor. Enable this signal by connecting it to either the connector ground or to an open-drain ground that will pull it below 0.5V. The maximum current that this signal will source is 10mA.

If the MessagePad is awake, the pulse is ignored. Timing for the prodDockAttach signal to wake the system is shown in Figure 1-3.

Figure 1-3 System WakeUp Timing

|<--- tWAKE --->|
prodDockAttach ---- \______________/ ---------


Table 1-3 System WakeUp Timing

Parameter Description Min Max
tWake Wake Up Pulse Width 1 msec 2 msec

AutoDocking

The prodDockAttach signal can also be used to alert the system that an external system peripheral has been attached to the MessagePad and that autodocking should be performed.

To perform autodocking, the prodDockAttach signal must be driven low, and must remain low until the dock is removed. The signal must remain low for at least 10msec to be recognized by the OS as a docking event.

If the unit is in the sleep state, the unit will awake once the prodDockAttach signal has been asserted. Timing is shown in Figure 1-4.

Figure 1-4 AutoDocking Timing

|<------ tDock ----->| |<------ tDock ----->|
prodDockAttach ---- \_________________ ____/ -----------------------------
Newton OS Validates ^ Newton OS knows the ^
Autodock Event autoDock Event is over


Table 1-4 AutoDocking Timing

Parameter Description Min Max
tDock prodDockAttach debounce time 10 msec --



Power Adapter Signals

The Newton Interconnect Port allows an external power source, such as an AC Power Adapter, to source 2-cell or 4-cell devices. The 2-cell devices are sourced through PowerInPos2, and 4-cell devices are sourced through PowerInPos4. All MessagePads built to date are 4-cell devices, so PowerInPos2 is not connected.

The Power Adapter is connected to five pins on the Newton Interconnect Port. The Power Adapter's positive voltage is applied to the PowerInPos4 signal on pins 2 and 14. The Power Adapter's ground is applied to the PowerInNeg signal on pins 3, 15, and 16.

Besides powering the unit, a Power Adapter can also charge the internal batteries (if a rechargeable battery pack is installed and properly detected).

Design specifications for a Power Adaptor that can source power to the MessagePad are described later in this document.



Connector Pinout

The following figures and tables illustrate the location of the signals on the Newton Interconnect Port. The connector pinout numbers are shown as they appear when looking into the respective connectors.

Figure 1-5 Newton Interconnect Port - MessagePad Side

----------------------------------------
|1---2--3--4--5--6--7--8--9-10-11-12-13|
|14-15-16-17-18-19-20-21-22-23-24-25-26|
\--------------------------------------/


Figure 1-6 Newton Interconnect Port - PeripheralSide

----------------------------------------
|13-12-11-10--9--8--7--6--5--4--3--2--1|
|26-25-24-23-22-21-20-19-18-17-16-15-14|
\--------------------------------------/


Table 1-5 Newton Interconnect Port Pin Assignments

Pin Number Signal Name I/O Signal Description
1 PowerInPos2 I Positive Power Adapter Input Voltage (2-cell systems)
2 PowerInPos4 I Positive Power Adaptor Input Voltage (4-cell systems)
3 PowerInNeg I Positive Adaptor Input Ground
4 auxAudOutPos O Audio Out (capable of driving a 1KW load)
5 AGnd O Auxiliary Audio Ground
6 SerialTXdP O Serial Channel 0 TX+
7 SerialGpi Serial Port/General Purpose Input
8 SerialRXdN I Serial Channel 0 RX-
9 Chan3TXd3 O Serial Channel 3 transmit
10 PortSel O Selects between Newton Interconnect Port and internal Serial Slot
11 dock5V O +5 Volt Supply
12 Chan3NotDTR I Serial Channel 3 Data Terminal Ready
13 ModemNotCTS O Serial Channel 3 Clear to Send
14 PowerInPos4 I Positive Power Adaptor Voltage (4-cell systems)
15 PowerInNeg I Power Adaptor Ground
16 PowerInNeg I Power Adaptor Ground
17 auxAudioIn I Audio Input
18 SerialTXdN O Serial Channel 0 TX-
19 SerialHsko O Serial Channel 0 Handshake Out
20 SerialHski I Serial Channel 0 Handshake In
21 SerialRxdP I Serial Channel 0 Rx+
22 Chan3Rxd3 I Serial Channel 3 RX
23 dGND O Digital Ground
24 Chan3RI3 I Serial Channel 3 Ring Indicator
25 ModemNotRTS3 Serial Channel 3 Not Request to Send
26 prodDockAttach Wakeup/Docking Signal


Table 1-6 Newton Interconnect Port Signal Groups

Power Signal Name Pin I/O Signal Description
PowerInPos2 1 I Positive Power Adaptor Input Voltage 2 Cell Systems
PowerInPos4 2, 14 I Positive Power Adaptor Input voltage 4 Cell Systems
PowerInNeg 3, 15, 16 I Power Adaptor Input Ground
dGND 23 I Digital Ground
dock5V 11 O +5 Volt Supply
Audio Signal Name Pin # I/O Signal Description
auxAudOutPos 4 O Line Level Audio Out
auxAudioIn 17 I Audio Input
AGnd 5 O Audio Ground
Serial Port 0 Signal Name Pin # I/O Signal Description
SerialTXdP 6 O Serial Channel 0 TX+
Serial Gpi 7 I Serial Port 0 General Purpose Input
SerialRXdN 8 I Serial Channel 0 RX-
SerialTXdN 18 O Serial Channel 0 TX-
SerialHsko 19 0 Serial Channel 0 Handshake Out
SerialHski 20 I Serial Channel 0 Handshake In
SerialRxdP 21 I Serial Channel 0 RX+
Serial Port 3 Signal Name Pin # I/O Signal Description
ChanTXd3 9 O Serial Channel 3 Transmit
Chan3NotDTR 12 I Serial Channel 3 Not Data Terminal Ready
ModemNotCTS 13 O Serial Channel 3 Not Clear to Send
Chan3Rxd3 22 I Serial Channel 3 RX
Chan3RI3 24 I Serial Channel 3 Ring Indicator
Chan3NotRTS3 25 Serial Channel 3 Request to Send
IntModemSel 10 O Enable for Internal Serial Channel 3
Control Signal Name Pin # I/O Signal Description
prodDockAttach 26 I Wakeup/Docking Signal


Output Connection for Newton Interconnect Connection

The Newton Interconnect Port requires a JAE 26-pin custom mating plug. This plug is available in locking and non-locking configurations. The non-locking configuration should be used when designing accessories that require smooth connection and have other mechanical means of securing the accessory to the MessagePad, such as a dock. The JAE part number for the non-locking connector is RX04-26P1-SF1.

The locking connector configuration should be used when designing accessories that require a more secure connection, such as a cable. The JAE part number for the locking connector is RX04-26P-SF1.

+5 Volt Power Supply

The Newton Interconnect Port has a +5V power supply that can be used to power external devices connected to the port. The supply is enabled by any of the following three events:
The total 5V power budget is 500mA, which must be shared by other devices in the system (such as PC Cards), in addition to the Newton Interconnect Port. Of this power budget, the Interconnect Port can draw a maximum of 100mA from the 5V power supply.

5-volt Power Supply Specifications

The section specifies the DC operating conditions for the 5V power source available on the Newton Interconnect Port.

Table 1-7 5-Volt Power Supply Voltages

Supply Min Voltage Max Voltage
Dock 5V 4.5V 5.5V

Table 1-8 Power Supply Current Specifications

Supply Min Voltage Max Voltage
Dock 5V --- 100mA



Power Adapter

This section defines the electrical criteria that a power adapter for the MessagePad must meet. The power adapter can be connected to the MessagePad via an external power adapter jack, other internal connectors, or the Newton Interconnect Port. When a power adapter is attached to any of these connections, and to an AC power source, it supplies the power to the system and can recharge batteries. If the power adapter is connected to the system, but not connected to an AC power source, it will draw a maximim of 100uA from the batteries.

DC Output Requirements

The output of the adapter must be designed to appear as a Thevenin equivalent source with an open circuit voltage of 6.75V to 7.50V, and have a source resistance of 0.2 Ohm to 0.4 Ohm over an output current range of 5mA to 1300mA.

When the current is below 5mA, the source voltage may not exceed 7.7V. The output from the adapter must be current-limited to between 1.1A and 1.3A, over the input voltage range of 4.5V to 7.0V.

Below an output of 4.0V, the current limit may be folded back or stepped back without damage. The following table gives the acceptable output range for several load conditions


Table 1-9 Constant Current Mode

Output Current (mA) Min.Voltage Limit (VDC) Max.Voltage Limit (VDC)
5 7.27 7.50
500 7.07 7.50
1000 6.87 7.50
1300 6.75 7.50


Table 1-10 Constant Voltage Mode

Output Voltage (VDC) Min.Current Limit (mA) Max.Current Limit (mA)
7.50 1100 1300
7.00 1100 1300
5.60 1100 1300
4.00 100 1300
0.00 0 1300


Table 1-11 Other Electrical Requirements

Parameter Nominal Max.
Ripple peak-to-peak - 100 mV
Leakage Current VIN - 0.75 mA
Instantaneous Over Voltage Protection 10.0 V 12.0 V
Figure 1-7 shows the Power Adapter's acceptable operating region.


Figure 1-7 Power Adapter Operating Range-Typical

(Omitted - too complex)




(The Newton Interconnect Specification was supplied with photocopies of the original engineering drawings of the Interconnect plug. Contact Apple Licensing if you need copies).