VTI Instruments EX1629 - Write_And_Copy_Scratchpad_2430

VTI Instruments Corp.
330 EX1629 Onboard Memory
Here is an example output from the READ_MEMORY command using the example code:
sent packet without errors
Packet length: 8
07 82 0A 03 22 F0 00 85
got a packet without errors on receive
Packet length: 39
26 82 00 0A 22 F0 00 AA 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10
11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1F 20 21
This is the same string that was in the WRITE_SCRATCHPAD, now has been transferred into
non-volatile memory.
WRITE_AND_COPY_SCRATCHPAD_2430
As noted above, the scratchpad is a volatile memory location. Between MLAN commands, the
1-Wire devices are powered down, and, hence, will lose all their scratchpad (volatile) data. In
example code below, the commands occur fast enough that power is not lost to the 1-Wire devices
and no data loss is experienced. This, however, is not recommended for a production environment.
As a consequence, the WRITE_AND_COPY command set is recommended. These commands are
atomic operations – they perform the write and the copy in a single MLAN command. Because the
read and write is accomplished in a single command, data integrity cannot be verified before it is
copied to memory (e.g. a READ_SCRATCHPAD command cannot be performed in the middle of
a WRITE_AND_COPY command set to verify the scratchpad write). However, the main memory
can still be checked after the write, in a separate series of MLAN operations to ensure that what
was written is correct.
int write_and_copy_scratchpad_2430(const char* data, int channel)
{
int sendLen, recLen = 0;
int i = 0;
char byte[3];
if(strlen(data) != ((DS2430_SCRATCHPAD_LEN * 2 ) +
(DS2430_SCRATCHPAD_LEN-1)))
{
printf("Data was not the right length (wanted 95, got %i)\n",
strlen(data));
return -1;
}
sendLen = 1; // reserve first byte for length
// access the current device with address in DATA_ID
SendPkt[sendLen++] = CMD_ML_ACCESS;
// construct a block of communication to MicroLAN
SendPkt[sendLen++] = CMD_ML_DATA;
SendPkt[sendLen++] = 3+DS2430_SCRATCHPAD_LEN; // block length
SendPkt[sendLen++] = 4+DS2430_SCRATCHPAD_LEN; // data length
// send the write scratchpad command
SendPkt[sendLen++] = WRITE_SCRATCHPAD;
// send the address byte
SendPkt[sendLen++] = 0;
// the bytes of data to write
for (i = 0; i < ((2*DS2430_SCRATCHPAD_LEN) +
(DS2430_SCRATCHPAD_LEN-1)); i+=3)
{
strncpy(byte, &data[i],2);
byte[2] = '\0';
SendPkt[sendLen++] = (uint8_t)strtoul(byte, NULL, 16); //convert
to hex
}