HT-CM400 NXP Semiconductors, HT-CM400 Datasheet - Page 36

• Manufacturer Part Number: HT-CM400
• Description: Ht Cm400; Ht Rm440 Family; Ht Rm800 Family Interface Protocol Reader - Host
• Manufacturer: NXP Semiconductors

Communication Reader-Host
3.7.21 ReadPit
This Proximity Reader command sets the read/write device to Permanent Reading Mode for PIT
transponders.
The read/write device attempts continuously to synchronize on and read a block of a PIT
transponder. If it succeeds and all checks report positive results, the device sends a block of 16
data bytes via the serial interface. After reading the specified number of data blocks, the
read/write device returns to Normal Mode.
To put the read/write device back to normal mode, a StopCommand should be sent. Do not use a
Reset, since Reset can cause undesirable side effects (resetting output pins).
ATTENTION:
If blknmb>1 to read several successive blocks, data must be read by the host-software in a special
manner. After having received the first block the host-software must place further ReadPit
commands for each new incoming block. It is important to place a new ReadPit as soon as
possible after data from the last ReadPit have been received and stored in a data-buffer.
Otherwise a data overflow can occur. This can be checked by reading the library-variable
RWDErr immediately before a new command ReadPit (RWDErr = -14 for PIT DATA
OVERFLOW). The further ReadPit commands mentioned above are only necessary, if the Philips
Semiconductors’ C-Library is used.
For further information see Header File PROLBPH6.h.
C-Function: void proloc_ReadPit (BYTE_T blknmb, BYTE_T next, char *data);
Header-File: PROLBPH6.H
Serial protocol:
HOST - READ/WRITE DEVICE
blknmb:
READ/WRITE DEVICE - HOST
Status:
Htswp.doc/HS
0x03
0x12
0x12
:
:
Status
Status
'T'
number of blocks to read
-1 ... SERIAL ERROR
0 ... no error
blknmb
data[0]
data[0]
BCC
....
....
data[15]
data[15]
Page 36 (104)
Rev. 1.0
BCC
BCC
98-02-10