JStamp Development Station

JStamp Development Station (JSDS) is a development board for JStamp. JSDS is included in the Development Kit and also available separately. It has dual JSimm sockets for prototyping and I/O expansion. JSDS is a standard 100x100 euroboard and fits our SnapTrack and Din Rail mounting kits.

	The JStamp Development Station (JSDS) includes a JStamp socket, dual RS-232 serial ports wired as DTE (these include true RS-232 level shifters but the level shifters can be disabled for TTL level asynchronous I/O on the JSimm bus), switching power regulator (6-24 VDC input), buzzer, power LED, 2 user LEDs (can be driven by I/O pins), a user pushbutton (can drive any I/O pin and/or generate interrupts), dual JSimm/SimmStick expansion sockets, an opto-22 compatible 25x2 100-mil IDC header, a JTAG access port for downloading and debugging JStamp, labelled headers for all I/O signals, and more. Click the image for a higher resolution photo.
JStamp Dev Station Quick Ref (1.2 MB)	Detailed quick reference including jumpers, pinouts, and detailed signal description table for the JStamp, JSimm bus and 25x2 I/O header.
JStamp pinout and signal description	JStamp's pins and interfacing them to common logic families.
JStamp Dev Station PCB 1.10 Schematics (500 KB)	JSDS schematics for PCB rev 1.10 which has the serial I/O paste jumpers on the back of the development station board.
JStamp Dev Station PCB 1.00 Schematics (500 KB)	JSDS schematics for PCB rev 1.00 which does not have paste jumpers to disconnect JStamp serial I/O from RS232 level shifters.

JStamp Development Station Serial I/O

The JStamp Development Station (JSDS) includes dual RS-232 serial ports wired as DTE. These include true RS-232 level shifters. The level shifters can be disabled for TTL level asynchronous I/O on the JSimm bus, or so that you can use those I/O pins for other purposes.

DTE, DCE, serial cables, ground/common, and null modems

JSDS serial I/O is wired as DTE (Data Terminal Equipment) with TXD on DB9M pin 3 and RXD on pin 2. PCs are also DTE, therefore the JSDS wires to peripherals the same as a PC would. Modems, printers, and other peripherals are typically DCE with their RXD on pin 3 and TXD on pin 2. There is no hardware handshaking on the JSDS. DTR (pin 4) and RTS (pin 7) are not connected. For all the details check the schematics above. DB9M pin 5 is ground or common. It does not need to be "earth ground". RS-232 serial-connected devices must share a common reference so that each device's signals are relative to the same zero value (the common or ground wire on the DB9). You can connect DTE to DCE with a straight serial cable. DCE to DCE or DTE to DTE requires a crossover or "null modem" cable so that each device's TXD is connected to the other's RXD and vice versa. One serial device has to talk on its TXD and the other has to listen to that signal with its RXD or you won't have a successful connection. This means you can connect JSDS to a serial printer or modem with a straight serial cable but must use a "null modem" or serial crossover cable to another JSDS or a PC.

Comments about "RS-232" devices and connecting to the JSDS

UART outputs are standardized and so are RS-232 level shifters. This standardization enables any standard UART to work with any standard RS-232, RS-485, RS-422, etc level shifter, and enables level shifters of different manufacturers to work together. True RS-XXX will work with true RS-XXX devices from any other vendor. JStamp alone has hardware UARTs and can interface to TTL level asynchronous serial I/O devices (you can't call TTL asynch devices "RS-232" since they are TTL level). "Asynchronous" and "RS-232" do not mean the same thing. JStamp development station *does* include RS-232 level shifters, as stated in the JSDS quick reference. "RS-232" -- if the term is properly applied -- means asynchronous serial I/O with RS-232 voltage levels. RS-232 levels are *always* inverted from TTL levels since all common RS-232 level shifters invert. Restating it: RS-232 level shifters *always* invert. That is part of the definition of RS-232 level shifters. There's no such animal as a non-inverting RS-232 level shifter. All Systronix products which state "RS-232" comply with RS-232 standards and interface with legitimate RS-232 voltage levels. Some companies use simpler/cheaper circuits which are not truly RS-232 compliant and do not always work with all possible RS-232 systems (such as notebooks, PDAs or other lower power systems which also "cheat" on the RS-232 spec). There can be valid reasons for doing this - power conservation and simplicity being two common ones. Typically, two systems which cheat on the spec will not work together reliably -- if at all. If we say "RS-232" on a Systronix product and don't have any other disclaimers, we really mean valid RS-232 levels and thresholds.