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Hardware expansion
Data logging to RAM PCMCIA cards
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DATA LOGGING TO
RAM PCMCIA CARDS

HARDWARE

RAM CARDS

RAM cards are only useful when 512k bytes or more of data have to be stored, and it must be done more quickly than Flash cards would allow. The fundamental difference in access is that Flash-ATA cards emulate hard disks but RAM cards do not. They have no 512 byte sector structure and can be written or read at random byte by byte.

See ADAPTER INSTALLATION, page 256, because it is the same for Flash, disk and RAM cards, but compile #DOSRAM.TDS to test the hardware, using its word DATALOG .

SUGGESTED ORDER

Production ceased September 2008 following an announcement over three years earlier in May 2005. The web shop is now closed.

To satisfy essential repair requirements, small quantites, sometimes on extended lead times, are available. .

POWER SUPPLY

A typical RAM card (not including the TDS2020F) takes about 1.9mA when operational. This was measured with a 12V supply and a 2-megabyte RAM card. It takes under 10A when turned off with CM-OFF .

SOFTWARE

FILES

Library files to support RAM cards are:

 

#CARD.TDS

Low-level access-the whole card appears at 32-bit addresses hex 100000 upwards.

#DOSRAM.TDS

Provides Windows and DOS emulation so that the card can be formatted and read in a PC with Explorer or Windows applications like Excel. The Windows file DATA.FIL appears at 32-bit addresses hex 100000 upwards.

 

During compilation of #DOSRAM.TDS, files #DOS.TDS and #CARD.TDS are also called.

TYPICAL TIMINGS

Turn off power to Card Memories using CM-OFF

940s

Turn on power to Card Memories using CARD

100ms

Write 16 bits using E!

112s

256k byte page change

1.05ms

Throughput, using 8-bit external A-D continuously (see file #FASTEST.TDS)

364,342 samples/s

Throughput, using 10-bit internal A-D under interrupt (see file #FASTAD.TDS)

41,000 samples/s


Each of the throughput measurements is limited to 256k bytes per run, after that a page change is needed.

RAM CARDS WITHOUT WINDOWS EMULATION

The TDS2020CM2 adapter maps RAM cards as several pages into the space hex 40000-7FFFF (256k bytes). To make addressing easier, the driver file #CARD.TDS hides the paging from the programmer and can be forgotten in most circumstances. The software gives the programmer a linear memory model spanning both the 32-pin socket on the TDS2020F and RAM card. This is the memory map of complete TDS2020F with TDS2020CM2 adapter and RAM card-addresses shown are 32-bit hex double numbers:

 

00000.

to

7FFFF.

below any 32-pin on-board chip

80000.

to

FFFFF.

on-board 32-pin memory chip

100000.

to

20FFFFF.

RAM memory card up to 32 megabytes

 

The whole of a card's RAM memory is made available in a 32-bit address space from hex 100000 upwards. For example a 4-megabyte RAM card memory is addressed from hex 100000 to 4FFFFF.

The key operations you can undertake are:

 

q       Initialise the system by including CARD at power-up and after being in standby.

q       To randomly read RAM card memories use commands EC@ E@ 2E@

q       To randomly write RAM card memories use commands EC! E! 2E!

q       To go to standby turn off the PCMCIA adapter with CM-OFF , then use STANDBY , or words from the file #TIMED.TDS. Remember to use CARD again after the standby period.

q       To view Attribute memory space issue ATTRIBUTE and use CARD to revert to regular memory space.

q       To view I/O space issue IO and use CARD to revert to regular memory space.

RAM CARDS WITH WINDOWS EMULATION

If you prefer, the RAM card can be formatted in a form acceptable to Windows or DOS using support file #DOSRAM.TDS. It can be done either on a PC or in the data-logger module. A file DATA.FIL is put onto the disk, occupying the entire card apart from the initial space used for DOS purposes. Like the non-DOS use, addresses hex 100000 and over are on the RAM card, this address being the first byte of the file DATA.FIL if DOS emulation is used.

Additional key operations you can undertake are:

 

q       To Windows format a RAM memory card on a TDS2020F
use CARD-FORMAT which will
1. write a boot 'sector',
2. allocate a single File Allocation Table filled with a single file,
3. allocate a single 'sector' for dictionary table and put in the
table one file DATA.FIL of maximum size.
Do not use a card memory formatted on TDS2020F (or on which you have logged data) for any normal PC purpose without reformatting on a PC.

q       To Windows format a RAM memory card on a PC:
1. Use the command FORMAT x: where x is the drive letter of
the PCMCIA slot. On some computers the PCMCIA drivers
provide an alternative format routine. When asked for a
volume name do not give one, just press return.
2. Use the PC routine DATAFILR.EXE to write a single file to
the RAM memory card, completely filling it.
3. Use
CARD in the TDS2020F to initialise hardware and
identify the start of the file DATA.FIL on the card.
When formatted on a PC typically some space is not available for data.

q       To log data write to successive bytes starting at 32-bit address CARD-START , which is hex 100000. When collection is complete write a marker word or string you'll recognise after the end of the data. One way to accomplish this is to use <CARD and CARD> to redirect serial output to the RAM card, giving the same 'serial-stream' method as used with Flash and hard disk cards. You must initialise the non-volatile 32-bit next-address variable POINTER on the card with the word SCRUB before using CARDEMIT or the redirection words <CARD & CARD>

q       To check for end of file don't write to address CARD-FINISH or beyond.

q       To update the date and time of DATA.FIL use the word STAMP .

q       To read collected data into a PC use any Windows copy facility. For example use Explorer to transfer the file DATA.FIL from the storage card to the PC. Your data starts at the beginning of the file and ends with the marker.

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