Datasheet

DS2438
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Recall Memory [B8hxxh]
This command recalls the stored values in EEPROM / SRAM page xxh to the scratchpad page xxh. This
command must proceed a Read SPxx command in order to read any page of memory on the DS2438.
Valid page numbers are 00h - 07h.
Convert T [44h]
This command begins a temperature conversion. No further data is required. The temperature conversion
will be performed, setting the TB flag in the Status/Configuration register to a “1” during conversion.
When the temperature conversion is done, the TB flag will clear to a “0”. If the bus master issues read
time slots following this command, the DS2438 will output “0” on the bus as long as it is busy making a
temperature conversion; it will return a “1” when the temperature conversion is complete.
Convert V [B4h]
This command instructs the DS2438 to initiate a voltage analog-to-digital conversion cycle. This sets the
ADB flag (see Status/Configuration register discussion in the Memory Map section). The voltage supply
that is measured is defined by the AD bit of the Status/Configuration register. When the A/D conversion
is done, the ADB flag is cleared and the current voltage value is placed in the VOLTAGE REGISTER of
page 00h. While an A/D conversion is taking place, all other memory functions are still available for use.
If the bus master issues read time slots following this command, the DS2438 will output “0” on the bus as
long as it is busy making a voltage measurement; it will return a “1” when the conversion is complete.
DS2438 COMMAND SET Table 11
INSTRUCTION DESCRIPTION PROTOCOL 1-WIRE BUS
MASTER STATUS
AFTER ISSUING
PROTOCOL
1-WIRE BUS
DATA AFTER
ISSUING
PROTOCOL
MEMORY COMMANDS
Read Scratchpad
Reads bytes from
DS2438 Scratchpad
page xxh
BEh <page
00h-07h>
Rx
<read up to nine
bytes of data>
Write Scratchpad
Writes bytes to
DS2438
Scratchpad page xxh
4Eh <page
00h-07h>
Tx
<write up to eight
bytes of data>
Copy Scratchpad
Copies entire contents
of Scratchpad page
xxh
to 8-byte EEPROM/
SRAM page xxh
48h<page
00h-07h>
Idle or Rx of NVB bit
{NVB bit in Status
Register = 1 until
copy complete (2-
10 ms, typ)}
Recall Memory
Copies entire contents
of EEPROM/SRAM
page xxh to
Scratchpad
page xxh
B8h<page
00h-07h>
Idle Idle
REGISTER COMMANDS
Convert T
Initiates temperature
conversion
44h Idle or Rx of TB bit
{TB bit in Status
Register = 1 until
conversion
complete}
Convert V
Initiates voltage A/D
conversion
B4h Idle or Rx of ADB bit
{ADB bit in Status
Register = 1 until
conversion
complete}