USB card for NUE-PSK modem … nearly ready!
Posted by: “George Heron N2APB”
Mon Sep 1, 2008 12:08 pm (PDT)
Here’s an update on the progress with the USB add-on project for the NUE-PSK Digital Modem … full details and photos, schematic, etc are on the modem website at www.nue-psk.com/usb.
The “NUE-USB” add-on card development is nearly complete and we are awaiting production cards from the fab house. We’ll start taking orders shortly and we can start shipping in about two weeks when the pc boards are received!
In a nutshell, the USB add-on card will make your NUE-PSK Digital Modem more flexible and more useful with its ability to record QSO receive and transmit text to a USB flash memory stick for archival and remote printing. The USB card also provides a serial connection to a PC, a port for a USB printer, and (soon) a real-time clock/calendar function to timestamp QSOs. The updated modem software contains the new keyboard commands for controlling the USB card functions, plus a wonderfully-revamped and consistent text editing commands.
The USB card fits into the existing modem enclosure with minimal modifications. The card occupies the battery compartment, since most users let us know that they would gladly sacrifice the use of internal batteries for this USB capability. (Battery operation of the modem is cool also a cool feature and it can indeed run up to 8 hours on a pair of 9V batteries, but we found that most people use the modem with an external source that also powers the transceiver.)
The USB card will be available for purchase in a variety of ways …
1) Fully assembled & tested — Make a few easy mods to your modem, load up the latest modem software, plug in the USB card and start recording QSOs!
2) Partial kit — PCB and all parts are supplied, with the LQFP 48-pin surface mount controller attached and programmed. You just attach the remaining parts.
3) Full Kit — PCB and all parts are supplied. You attach the LQFP 48-pin surface mount controller and program it yourself with a PC serial port and free software.
4) Modified Enclosure (optional) — Lower half of the aluminum enclosure clamshell with mounting and connector/LED access holes.
5) Full Factory Upgrade — Don’t want to do any of this yourself? Just send us your modem and we’ll return it with the USB card fully installed and operational.
Prices are not yet established, but we’ll be keeping them as low as possible to make it easy for modem owners to upgrade. We’ll be announcing prices next week (Sept 8th) and will start accepting orders then. Meanwhile check out other details below …
USB Card Features …
1) Recording Rx and Tx text from the LCD to a USB flash drive (memory stick) — The main intent of the “recording” feature is to capture the Tx and Rx text streams for later archiving and/or printing from one’s PC. The “recording” function we are putting into the software and the file that we are saving to the USB stick captures whatever is coming across the LCD. Whatever you type during Tx mode, and whatever you see in Rx mode is exactly what gets saved away during our “logging” process. (This is in contrast to any kind of a formatted, standards-based, time stamped line of data containing callsigns, signal reports, etc. We will not be doing this type of extensive formatting in the modem – it is just too much effort and there is not enough code space to deal with this.)
2) USB Flash Drive Boot Loading — With the ability to read data from the USB memory stick comes the feature of boot loading new modem software loads directly from the stick, instead of needing to be tethered to the PC serial port for programming new versions of modem software. In fact, one can have multiple software versions on the USB stick, each containing support for different modes of operation (PSK31, RTTY, CW, et al) … just plug in the thumb drive and load in the desired mode you wish to operate! This will be convenient, as in the near-term we intend to provide separate software versions for the different modes of operation. (The current software architecture and memory availability in the dsPIC memory prohibits co-resident modem algorithms.)
3) Built-in USB connection to the PC for “field programming” of modem software updates — Once the modem is updated with the latest software (containing the USB feature support), the USB card’s “B” connector will allow a USB Host cable connection to the PC for download and programming of new software releases, as well as for communication with other devices.
4) Built-in USB printer port — Provides for realtime printing of the Tx & Rx data streams (the same, raw Rx and Tx QSO data, as seen on the LCD.) [Software support not yet available … popular printer protocols will come in later software releases after initial deployment of the USB card.]
5) Built-in Real-Time Clock/Calendar (pcb traces only) — Provisions have been made on the board to support a PIC controller in order to maintain current date and time, ultimately for use by the modem and in the recorded data going to the USB memory stick. Other than the schematic and board layout supporting the PIC circuitry, this feature has not yet been designed – it is hoped that others will help out by adding to the Open Software modem project. The task involves designing the PIC software and hooks in the modem’s dsPIC software … a separate Modem RTCC requirements document is available for those wishing to help with the project.
Design Notes …
The USB board plugs into the main board by means of a mating female connector to the modem’s P4 “Field Programming” pinheader. Minor and easy mods are required on the modem pcb to supply 5 volts to the P4 connector (instead of 3.3V), and to bring two extra control lines out to a new connector that plugs into the USB card. The USB card is the same y-dimension as the modem board, and it extends 1-1/8″ in the x-direction over to the left edge of the enclosure. The board sits even with the main board, supported by two standoffs on the left side and a 4-position SIP female header on the bottom that extends out the right side of the board to plug into the existing P4 connector.
The heart of the design is the Vinculum VNC1L FTDI controller chip. Although more expensive than “USB bit banging” alternatives, the VNC1L chip provides support for the full USB protocol control, and a DOS-like command line interpreter that allows easy writing and reading of a flash disk, making it a relatively easy design-in for USART ports such as we have available on the NUE-PSK modem. (For a great overview of the product, see the July 2007 issue 204 of Circuit Cellar magazine http://www.circuitcellar.com). Additionally, the VNC1L chip offers Host mode support, which allows the USB card to serve as the “serial interface” to a PC, providing a way to load modem software into the dsPIC as before, as well as providing communications to other devices downstream.
A real-time clock/calendar (RTCC) function is optionally possible on the USB card in order to keep track of date and time, even with the power removed from the modem. The concept is that the PIC monitors the modem’s UART port for an “RTCC data request”, whereupon the PIC switches data path to send the date and time information to the dsPIC. The new/replacement bottom half of the enclosure will continue to have the battery cover plate present to allow accessing the coin-sized battery that powers the RTC circuit. (NOTE: Although the RTCC circuit traces indicated in the schematic are indeed provided on the traces of the pc board, the RTCC functions and components are not provided in the initial NUE-USB cards being sold. We did not have time to complete this lesser-important product capability, so we put the framework in place with hopes that some one else can step up to help with this Open Source design.)
73, George N2APB & Milt W8NUE