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di194.c File Reference

Implementation of the DI-194 code, routines, etc. More...

#include "di194.h"
#include "di194-internal.h"

Go to the source code of this file.

Functions
int	di_serial_close (const int COMM_FD)
	Simple wrapper to close the port.
int	di_serial_init (const char *COMPORT_FILE)
	Open port and configure control lines, etc.
int	min (const int A, const int B)
	Hardwired min fn.
void	hex_print_byte (const uint8_t in_byte)
	Super-quick hack to hex-print a character, with ASCII if printable.
int	di_stop (const int COMM_FD)
int	di_start (const int COMM_FD)
int	di_reset (const int COMM_FD)
int	di_serial_num (const int COMM_FD, char *ser_buf)
int	di_serial_read (const int COMM_FD, const uint8_t *buf, const int READ_LEN, const time_t TIMEOUT)
	Read with timeout from a file descriptor.
void	di_cmd_print (const uint8_t *cmd, const int CMD_LEN)
	Debug routine to print a command to stderr.
bool	is_reset_cmd (const uint8_t *cmd, const int CMD_LEN)
	Function to compare an input command to the reset command.
int	di_daq_sync (const int COMM_FD)
	Function to re-sync with the incoming stream of samples.
int	di_cmd_send (const int COMM_FD, const uint8_t *cmd, const int CMD_LEN)
	Send a command to the unit and get the reply.
int	di_initialize (const int COMM_FD, int *num_bits)
	Function to init comms with a DI-194 once the port is setup.
int	di_configure (const int COMM_FD)
	Program DI-194 for continuous DAQ.
char *	di_byte_print (const uint8_t in_byte)
	Nasty hack to print a byte as bits.
int	di_buf_validate (const daq_buf_t buf)
	Check that a buffer matches the expected structure.
int	di_buf_decode (const daq_buf_t buf, daq_reading_t *result, const int NUM_BITS)
	Convert from raw data into float, raw and bit format.
int	di_open (const char *COMPORT_FILE, int *num_bits)
	User-called routine to open the port, program DI194.
int	di_close (const int COMM_FD)
	Shut down DI194.
int	di_read (const int COMM_FD, daq_reading_t *data, const int NUM_BITS)
	User-called routine to read one data point. Or something like 1.
int	di_read_single (const int COMM_FD, daq_reading_t *data, const int NUM_BITS)
	User-called routine to read one data point. Assumes unit stopped.
Variables
bool	do_exit
	Global boolean set only by interrupt handler to indicate break.

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Detailed Description

Implementation of the DI-194 code, routines, etc.

Simple code to read and program the Dataq DI-194, a $13 serial-port based DAQ card. It'll do 60Hz on its four analog input channels + 3 digital input bits.

This code started out as an undocumented file, here is the original attribution:

Author: Anthony Hanson and Mike Hage Date: April 1st, 2001

Many changes, cleanup and so forth on my part. I've basically rewritten the entire code, using the original to understand commands and parameters.

Author:

Paul Hubbard phubbard@computer.org

Date:

2/2002

Definition in file di194.c.

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Function Documentation

int di_buf_decode (  const daq_buf_t  buf, daq_reading_t *  result, const int  NUM_BITS )

Convert from raw data into float, raw and bit format. Function to decode a block of eight bytes encoded from a DATAQ DI-194 as explained in the app note, which should have been included with this file. Expects 8-byte input buffer, zero terminated Data in 194 format (make some checks) Result buffer ready to fill Returns Struct filled in, with bit set if OK, otherwise return non-zero Notes Neither overly paranoid nor overly optimized. Parameters: buf  Buffer as read from the DI-194 result  Pointer to struct that we will fill with decoded data Returns: 0 Success 1 Invalid buffer Date: 3-3-02 Definition at line 818 of file di194.c. References daq_reading_t::analog, di_buf_validate(), daq_reading_t::digital, hex_print_byte(), daq_reading_t::is_valid, and daq_reading_t::raw. Referenced by di_read().

int di_buf_validate (  const daq_buf_t  buf  )

Check that a buffer matches the expected structure. Function to check the first couple of bytes for the signature that should be there if they are a valid DI-194 reading. See the Dataq sheet for details; there are some bits hardwired to zero that we check for. Note that random data can easily confuse this into returning valid on bad data; this is _not_ robust. Assumes Can check up the whole buffer Returns 0 if valid, nonzero if invalid Parameters: buf  Ptr to buffer that we are to check out Returns: 0 Buffer is valid Non-zero Buffer is not valid, invalid LSB at index - 1 returned Date: 3/13/01 Definition at line 770 of file di194.c. Referenced by di_buf_decode(), and di_daq_sync().

char* di_byte_print (  const uint8_t  in_byte  )

Nasty hack to print a byte as bits. Warning: Uses a static buffer, so not threadsafe! Parameters: in_byte  Byte to print out Returns: char* != NULL Success; pointer to buffer to print NULL Error! Date: 3/13/02 Definition at line 726 of file di194.c.

int di_close (  const int  COMM_FD  )

Shut down DI194. Parameters: COMM_FD  File descriptor of connected port Returns: 0 Closed OK Non-zero An error occurred Date: 4-12-02 Definition at line 988 of file di194.c. References di_serial_close(). Referenced by daq_loop(), main(), and user_loop().

void di_cmd_print (  const uint8_t *  cmd, const int  CMD_LEN )

Debug routine to print a command to stderr. Parameters: cmd  Pointer to the command to send CMD_LEN  Length of command, in bytes Definition at line 324 of file di194.c.

int di_cmd_send (  const int  COMM_FD, const uint8_t *  cmd, const int  CMD_LEN )

Send a command to the unit and get the reply. Function to send a command to the DI-194, and discard the echod response. The DI seems to echo the non-zero characters sent, but with some exceptions. Most annoying. More exactly: it never echos the leading zero a rejected / unknown command echos 0xFF back arguments are echod verbatim unless the command is reset a reset command echos one extra byte back to the sender All of this was determined experimentally and may therefore be wrong. Parameters: COMM_FD  File descriptor of the serial port cmd  Pointer to command to send CMD_LEN  Length of command, in bytes Returns: 0 Success Non-zero An error occurred Date: 3/2002 Definition at line 502 of file di194.c. References di_serial_read(), and serial_timeout. Referenced by di_configure(), di_initialize(), di_reset(), di_serial_num(), di_start(), and di_stop().

int di_configure (  const int  COMM_FD  )

Program DI-194 for continuous DAQ. Note: Currently hardwired for 240Hz on channel 1 + digital If DI194_OLD_UNIT is defined, sends enable code from old source Function to program the DI-194 for continuous sampling, for now it turns on all channels. This yields 60Hz, one can get to 240 by only sampling one channel. This is due to the 4800 baud transfer rate, and by the fact that the encryption table uses two bytes per analog sensor. Assumes Port opened and init'd OK Parameters: COMM_FD  File descriptor of serial port Returns: 0 Success- all programming seemed to work non-zero Error Date: 3/6/02 Definition at line 676 of file di194.c. References all_chan, di_cmd_send(), and dig_chan. Referenced by di_open(), and user_loop().

int di_daq_sync (  const int  COMM_FD  )

Function to re-sync with the incoming stream of samples. We may be off by up to seven bytes due to sync errors, so read two buffers' worth and look for the signature as spec'd in the DATAQ web page. Kind of a hack until I grok more about the protocol. Assumes DI-194 is streaming data to the given port Parameters: COMM_FD  File descriptor of the serial port Returns: 0 Sync'd OK and next read should be valid Non-zero No sync, or other error occurred Date: 3/13/02 Definition at line 417 of file di194.c. References daq_buf_t, di_buf_validate(), di_serial_read(), and serial_timeout. Referenced by daq_loop(), main(), and user_loop().

int di_initialize (  const int  COMM_FD, int *  num_bits )

Function to init comms with a DI-194 once the port is setup. Does a reset, downloads the key, and requests the serial number from the unit - should make a good test. Assumes Port open, 194 connected to same Parameters: COMM_FD  File descriptor of serial port Returns: 0 Success Non-zero An error occurred Date: 3/4/02 Definition at line 589 of file di194.c. References di_cmd_send(), di_enable_key, di_serial_num(), di_stop(), key_cmd, odd_cmd, and SERIAL_NUM_LEN. Referenced by di_open().

int di_open (  const char *  COMPORT_FILE, int *  num_bits )

User-called routine to open the port, program DI194. Note: Uses contents of "DI194_PORT" environment variable if set and COMPORT_FILE is null Main. Open the port, init the card, do some daq. To do: -p port parsing, will need for USB serial. getopt! Parameters: COMPORT_FILE  Path to device Returns: >0 All is good, return value is file descriptor <= 0 All is not good, no guarantees Definition at line 914 of file di194.c. References di_configure(), di_initialize(), and di_serial_init(). Referenced by daq_loop(), and main().

int di_read (  const int  COMM_FD, daq_reading_t *  data, const int  NUM_BITS )

User-called routine to read one data point. Or something like 1. Warning: Will block until data available Assumes adequate buffering; does not re-sync Date: 4-12-02 Parameters: COMM_FD  File descriptor of ready port data  Ptr to struct for returned data Returns: 0 Data is OK and read Non-zero An error occurred Definition at line 1021 of file di194.c. References daq_buf_t, di_buf_decode(), di_serial_read(), and serial_timeout. Referenced by daq_loop(), di_read_single(), main(), and user_loop().

int di_read_single (  const int  COMM_FD, daq_reading_t *  data, const int  NUM_BITS )

User-called routine to read one data point. Assumes unit stopped. Warning: Will block until data available Assumes adequate buffering; does not re-sync Date: 5-19-02 Parameters: COMM_FD  File descriptor of ready port data  Ptr to struct for returned data Returns: 0 Data is OK and read Non-zero An error occurred Definition at line 1077 of file di194.c. References di_read(), di_start(), and di_stop(). Referenced by user_loop().

int di_reset (  const int  COMM_FD  )

Definition at line 205 of file di194.c. References di_cmd_send(), and rst_cmd. Referenced by user_loop().

int di_serial_close (  const int  COMM_FD  )

Simple wrapper to close the port. ... which releases the control lines and shuts down the DAQ. Parameters: COMM_FD  File descriptor of the opened serial port to be closed Return values: 0  Completed OK Non-zero  An error occurred Date: 3/11/02 Note: minor changes from original Definition at line 50 of file di194.c. Referenced by di_close().

int di_serial_init (  const char *  COMPORT_FILE  )

Open port and configure control lines, etc. Function to open the serial port and set up the rather peculiar comms requirements of the DI-194: 4800 baud, N81 No flow control (?) Controlled by DTR? Parameters: COMPORT_FILE  Pointer to filename to open, not modified Returns: 0 Operation successful Non-zero An error occurred Date: 3/11/02 Note: cleaning up original code, no substantial changes Definition at line 82 of file di194.c. References serial_timeout. Referenced by di_open().

int di_serial_num (  const int  COMM_FD, char *  ser_buf )

Definition at line 210 of file di194.c. References di_cmd_send(), di_serial_read(), SERIAL_NUM_LEN, serial_timeout, and sn_cmd. Referenced by di_initialize(), and user_loop().

int di_serial_read (  const int  COMM_FD, const uint8_t *  buf, const int  READ_LEN, const time_t  TIMEOUT )

Read with timeout from a file descriptor. Parameters: COMM_FD  File descriptor of serial port in use buf  Buffer to write data into READ_LEN  Number of bytes to be read TIMEOUT  Max wait, in seconds Returns: 0 Success Non-zero An error occurred Warning: Not foolproof! Does not use select Note: Coarse granularity - integer seconds Definition at line 266 of file di194.c. Referenced by di_cmd_send(), di_daq_sync(), di_read(), and di_serial_num().

int di_start (  const int  COMM_FD  )

Definition at line 200 of file di194.c. References di_cmd_send(), and start_cmd. Referenced by daq_loop(), di_read_single(), main(), and user_loop().

int di_stop (  const int  COMM_FD  )

Definition at line 194 of file di194.c. References di_cmd_send(), and stop_cmd. Referenced by di_initialize(), di_read_single(), and user_loop().

void hex_print_byte (  const uint8_t  in_byte  )

Super-quick hack to hex-print a character, with ASCII if printable. Note: Strictly a debug aid. Parameters: in_byte  Character to be printed Returns: void Definition at line 187 of file di194.c. Referenced by di_buf_decode().

bool is_reset_cmd (  const uint8_t *  cmd, const int  CMD_LEN )

Function to compare an input command to the reset command. Just an inline cleanup Assumes CMD and len match Returns true if matches rst_cmd, false otherwise or if NULL Parameters: cmd  Pointer to command in question CMD_LEN  Length of command in question Returns: true cmd is a reset request false Not a reset request, or an error occurred Date: 3/11/02 Definition at line 375 of file di194.c. References rst_cmd.

int min (  const int  A, const int  B )

Hardwired min fn. Here and I thought min(int, int) was part of C9X now. Hmm. Parameters: A  First value to be compared B  Second value to be compared Returns: A A is <= B B B is <= A Definition at line 171 of file di194.c.

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Variable Documentation

bool do_exit

Global boolean set only by interrupt handler to indicate break. Definition at line 30 of file di194.c. Referenced by daq_loop(), main(), main_loop(), sighandler(), and user_loop().

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