CFA633-RDI-KS datasheet(69/88 Pages) CRYSTAIFONTZ

69 / 88 page

Crystalfontz America, Inc.

Data Sheet Release Date 2012/02/21

www.crystalfontz.com

CFA633-RDI-KS LCD Module (Hardware v2.0 / Firmware s2v1)

February 2012

Page 69

To demonstrate reading and writing the scratch memory on DS1963S, open the 633_WinTest Packet Debugger dialog

and use it to experiment with the following commands: Erase Scratchpad, Read Scratchpad, and Write Scratchpad.

To use the full power of the DS1963S, a program based on the Dallas/Maxim application notes listed above is needed.

The challenge/response sequence would be unwieldy to demonstrate using the 633_WinTest Packet Debugger dialog.

First read the address of the DS1963S as detected by the CFA633 at boot. Since only one device is connected, you only

need to query index 0. In a production situation, query all 32 indices to get a complete picture of the devices available

on the DOW bus.

Command:

18 = Read DOW Device Information

Data sent:

\000

Data received:

C=82(d=0):18,CC,D2,19;00,00,00,9E

The first byte returned is the Family Code of the Dallas One Wire / iButton device. 0x18 indicates that this device is a

DS1963. A list of the possible Dallas One Wire / iButton device family codes is available in App Note 155: 1-Wire

Software Resource Guide on the Maxim/Dallas website.

Erase Scratchpad Command (quote from the Maxim/Dallas DS1963S Data Sheet):

Erase Scratchpad [C3h]

The purpose of this command is to clear the HIDE flag and to wipe out data that might have been left in the

scratchpad from a previous operation. After having issued the command code the bus master transmits a target

address, as with the write scratchpad command, but no data. Next the whole scratchpad will be automatically

filled with FFh bytes, regardless of the target address. This process takes approximately 32 µs during which the

master reads 1’s. After this the master reads a pattern of alternating 0’s and 1’s indicating that the command

has completed. The master must read at least 8 bits of this alternating pattern. Otherwise the device might not

properly respond to a subsequent Reset Pulse.

Command:

20 = Arbitrary DOW transaction

Data sent:

\000\014\xC3\000\000

Data received:

C=84(d=0):FF,AA,AA,AA,AA,AA,AA,AA,AA,AA,AA,AA,AA,AA,9F

The “AA” bytes read are the pattern of alternating 0’s and 1’s indicating that the command has completed.

Read Scratchpad Command (quote from the Maxim/Dallas DS1963S Data Sheet)

Read Scratchpad Command [AAh]

HIDE = 0:

The Read Scratchpad command allows verifying the target address, ending offset and the integrity of the

scratchpad data. After issuing the command code the master begins reading. The first 2 bytes will be the target

address. The next byte will be the ending offset/data status byte (E/S) followed by the scratchpad data

beginning at the byte offset (T4: T0). The master may read data until the end of the scratchpad after which it will

receive the inverted CRC generated by the DS1963S. If the master continues reading after the CRC all data

will be logic 1’s.

Command:

20 = Arbitrary DOW transaction

Data sent:

\000\014\xAA

Data received:

C=84(d=0):00,00,1F,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,07

Since you did an "Erase Scratchpad” as the previous command, the "Read Scratchpad” returns 0xFF bytes as expected.

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