Added an optional engine_delay parameter to work around potential engine

instability problems for CIS models.

ChangeLog

@@ -1,3 +1,9 @@
+2005-10-22  Eddy De Greef <eddy_de_greef at tiscali dot be>
+
+	* backend/mustek_pp_cis.c backend/mustek_pp_cis.h
+          doc/sane-mustek_pp.man: Added an optional engine_delay parameter
+          to work around potential engine instability problems for CIS models.
+
 2005-10-21  Gerhard Jaeger <gerhard@gjaeger.de>
 
 	* doc/plustek/Plustek-USB.changes: Update.

backend/mustek_pp_cis.c

@@ -95,6 +95,9 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <math.h>
+#ifdef HAVE_SYS_SELECT_H
+# include <sys/select.h>
+#endif
 #include "../include/sane/sane.h"
 #include "../include/sane/sanei_pa4s2.h"
 #define DEBUG_DECLARE_ONLY
@@ -1089,8 +1092,19 @@ cis_config_ccd (Mustek_PP_CIS_dev * dev)
 static SANE_Bool
 cis_wait_motor_stable (Mustek_PP_CIS_dev * dev)
 {
-   return Mustek_PP_1015_wait_bit (dev, MA1015R_MOTOR, MA1015B_MOTOR_STABLE, 
-                                   SANE_FALSE, 0);
+   static struct timeval timeoutVal;
+   SANE_Bool ret = 
+      Mustek_PP_1015_wait_bit (dev, MA1015R_MOTOR, MA1015B_MOTOR_STABLE, 
+                               SANE_FALSE, 0);
+#ifdef HAVE_SYS_SELECT_H
+   if (dev->engine_delay > 0)
+   {
+      timeoutVal.tv_sec = 0;
+      timeoutVal.tv_usec = dev->engine_delay*1000;
+      select(0, NULL, NULL, NULL, &timeoutVal);
+   }
+#endif
+   return ret;
 }
 
 static void
@@ -1998,8 +2012,7 @@ cis_measure_delay(Mustek_PP_CIS_dev * dev)
 static void
 cis_motor_control (Mustek_PP_CIS_dev * dev, u_char control)
 {
-   Mustek_PP_1015_wait_bit(dev, MA1015R_MOTOR, MA1015B_MOTOR_STABLE, 
-                           SANE_FALSE, 0);
+   cis_wait_motor_stable (dev);
    Mustek_PP_1015_write_reg(dev, MA1015W_MOTOR_CONTROL, control);
 }
 
@@ -2126,7 +2139,7 @@ cis_calibrate (Mustek_PP_CIS_dev * dev)
       {
          Mustek_PP_1015_write_reg_val (dev, 0x7B);
       }
-      Mustek_PP_1015_wait_bit(dev, MA1015R_MOTOR, MA1015B_MOTOR_STABLE, SANE_FALSE, 0);
+      cis_wait_motor_stable (dev);
    }
    Mustek_PP_1015_write_reg_stop(dev);
    
@@ -2383,6 +2396,7 @@ void cis_drv_setup (SANE_Handle hndl)
    cisdev->fast_skip = SANE_TRUE;
    cisdev->bw_limit = 127;
    cisdev->calib_mode = SANE_FALSE;
+   cisdev->engine_delay = 0;
    if (cisdev->model == MUSTEK_PP_CIS600)
    {
       cisdev->top_skip = MUSTEK_PP_CIS_600CP_DEFAULT_SKIP;
@@ -2459,7 +2473,7 @@ SANE_Status cis_drv_config(SANE_Handle hndl, SANE_String_Const optname,
       value = atoi(optval);
       if (value < 0 || value > 255)
       {
-         DBG (1, "cis_drv_config: valu for option bw out of range: "
+         DBG (1, "cis_drv_config: value for option bw out of range: "
                  "%d < 0 or %d > 255\n", value, value);
          return SANE_STATUS_INVAL;
       }
@@ -2475,6 +2489,22 @@ SANE_Status cis_drv_config(SANE_Handle hndl, SANE_String_Const optname,
       DBG (3, "cis_drv_config: using calibration mode\n");
       cisdev->calib_mode = SANE_TRUE;
    }
+   else if (!strcmp(optname, "engine_delay"))
+   {
+      if (!optval)
+      {
+         DBG (1, "cis_drv_config: missing value for option engine_delay\n");
+         return SANE_STATUS_INVAL;
+      }
+      value = atoi(optval);
+      if (value < 0 || value > 100) /* 100 ms is already pretty slow */
+      {
+         DBG (1, "cis_drv_config: value for option engine_delay out of range: "
+                 "%d < 0 or %d > 100\n", value, value);
+         return SANE_STATUS_INVAL;
+      }
+      cisdev->engine_delay = value;
+   }
    else
    {
       DBG (1, "cis_drv_config: unknown options %s\n", optname);

backend/mustek_pp_cis.h

@@ -226,6 +226,8 @@ typedef struct Mustek_PP_CIS_dev
   SANE_Byte bw_limit; 
   /* Run in calibration mode ? (default: no) */
   SANE_Bool calib_mode;
+  /* Extra delay between engine commands (ms). Default: zero. */
+  SANE_Int engine_delay;
   
   /* temporary buffer for 1 line (of one color) */
   SANE_Byte *tmpbuf;

doc/sane-mustek_pp.man

@@ -65,13 +65,15 @@ Targa
    Funline TS6EP        600 CP     yes
 Trust  
    Easy Connect 9600+   600 CP     yes
+Cybercom 
+   9352                1200 CP     yes (***)
 .fi
 .ft R
 .RE
 
 .PP
 .HP 
-(*)   Calibration  problems existed with earlier version of
+(*)    Calibration  problems existed with earlier version of
 this driver. They seem to be solved now.
 .HP 
 (**)   Problems have been reported in the past for the
@@ -81,6 +83,9 @@ the current version of the driver still has these problems.
 .br
 .B  IF YOU HEAR LOUD CLICKING NOISES, IMMEDIATELY UNPLUG THE SCANNER !
 (This holds for any type of scanner).
+.HP 
+(***)  Possibly, the engine_delay parameter has to be set to 1 ms
+for accurate engine movements.
 .PP
 
 
@@ -275,6 +280,32 @@ no models for which these inaccuracy problems are known to occur.
 By default, fast skipping is used.
 .PP
 Example:  option slow_skip
+.HP
+.B engine_delay <value>
+Under normal circumstances, it is sufficient for the driver to wait for the
+scanner signaling that the engine is stable, before a new engine command can
+be transmitted. In rare cases, certain scanners and/or parallel port chipsets
+appear to prevent reliable detection of the engine state. As a result, engine
+commands are transmitted too soon and the movement of the scanner head becomes
+unreliable. Inaccuracies ranging up to 10 cm over the whole vertical scan
+range have been reported. To work around this problem, the engine_delay option
+can be set. If it is set, the driver waits an additional amount of time after
+every engine command, equal to the engine_delay parameter, expressed in
+milliseconds. It practice an engine_delay of 1 ms is usually sufficient. The
+maximum delay is 100 ms.
+.br
+Note that every additional ms of delay can add up to 14 seconds to the total
+scanning time (highest resolution), so an as small as possible value is
+prefered.
+.br
+Default value:   0
+.br
+Minimum:         0
+.br
+Maximum:       100
+.br
+.PP
+Example:  option engine_delay 1
 .PP
 .RE
 .TP