Merge pull request #74 from tvoverbeek/PUstagetime

Implement Fast Update by setting stage time directly

@CharmingSu @repaper pulling in this PR as haven't heard from you. If you have any objection please let us know

PlatformWithOS/README.md

@@ -104,6 +104,7 @@ panel        Read Only    String describing the panel and giving its pixel width
 current      Read Only    Binary image that  matches the currently displayed image (big endian)
 display      Read Write   Image being assembled for next display (big endian)
 temperature  Read Write   Set this to the current temperature in Celsius
+f_stage_time Read Write   Set stage time in milliseconds for 'F' command
 command      Write Only   Execute display operation
 BE           Directory    Big endian version of current and display
 LE           Directory    Little endian version of current and display
@@ -112,6 +113,8 @@ Command   Byte   Description
 --------  -----  --------------------------------
 'C'       0x43   Clear the EPD, set `current` to all zeros, `display` is not affected
 'U'       0x5A   Erase `current` from EPD, output `display` to EPD, copy display to `current`
+'P'       0x50   Do partial update of display by only updating the changed parts
+'F'       0x46   Same as partial update, but use user defined stage time
 
 Notes:
 

PlatformWithOS/driver-common/V110_G1/epd.c

@@ -463,6 +463,10 @@ void EPD_set_temperature(EPD_type *epd, int temperature) {
 	epd->factored_stage_time = epd->stage_time * temperature_to_factor_10x(temperature) / 10;
 }
 
+void EPD_set_factored_stage_time(EPD_type *epd, int pu_stagetime) {
+        epd->factored_stage_time = pu_stagetime;
+}
+
 // clear display (anything -> white)
 void EPD_clear(EPD_type *epd) {
 	frame_fixed_repeat(epd, 0xff, EPD_compensate);

PlatformWithOS/driver-common/V110_G1/epd.h

@@ -66,6 +66,9 @@ void EPD_destroy(EPD_type *epd);
 // set the temperature compensation (call before begin)
 void EPD_set_temperature(EPD_type *epd, int temperature);
 
+// set factored_stage_time directly ('F' command)
+void EPD_set_factored_stage_time(EPD_type *epd, int pu_stagetime);
+
 // sequence start/end
 void EPD_begin(EPD_type *epd);
 void EPD_end(EPD_type *epd);

PlatformWithOS/driver-common/V231_G2/epd.c

@@ -492,6 +492,10 @@ void EPD_set_temperature(EPD_type *epd, int temperature) {
 	epd->factored_stage_time = epd->base_stage_time * temperature_to_factor_10x(temperature) / 10;
 }
 
+void EPD_set_factored_stage_time(EPD_type *epd, int pu_stagetime) {
+	epd->factored_stage_time = pu_stagetime;
+}
+
 
 // clear display (anything -> white)
 void EPD_clear(EPD_type *epd) {

PlatformWithOS/driver-common/V231_G2/epd.h

@@ -71,6 +71,9 @@ void EPD_destroy(EPD_type *epd);
 // set the temperature compensation (call before begin)
 void EPD_set_temperature(EPD_type *epd, int temperature);
 
+// set factored_stage_time directly ('F' command)
+void EPD_set_factored_stage_time(EPD_type *epd, int pu_stagetime);
+
 // sequence start/end
 void EPD_begin(EPD_type *epd);
 void EPD_end(EPD_type *epd);

PlatformWithOS/driver-common/epd_fuse.c

@@ -49,13 +49,16 @@ static const char *display_path          = "/display";          // the next imag
 static const char *display_inverted_path = "/display_inverse";  // the next image to display
 static const char *command_path          = "/command";          // any write transfers display -> EPD and updates current
 static const char *temperature_path      = "/temperature";      // read/write temperature compensation setting
+static const char *pu_stagetime_path     = "/pu_stagetime";     // stagetime to use for 'F' command,
+                                                                // bypassing temperature compensation.
 static const char *error_path            = "/error";            // error text
 static const char *spi_device = SPI_DEVICE;        // default SPI device path
 static const uint32_t spi_bps = SPI_BPS;           // default SPI device speed
 
 // expect that external process changes this just before update command
 // by sending text string e.g. shell:  echo 19 > /dev/epd/temperature
 static int temperature = 25;                       // for external temperature compensation
+static int pu_stagetime = 500;                     // stagetime to use in 'F' command
 
 #define MAKE_STRING_HELPER(s) #s
 #define MAKE_STRING(s) MAKE_STRING_HELPER(s)
@@ -184,6 +187,11 @@ static int display_getattr(const char *path, struct stat *stbuf) {
 		stbuf->st_nlink = 1;
 		stbuf->st_size = 4;
 
+	} else if (strcmp(path, pu_stagetime_path) == 0) {
+		stbuf->st_mode = S_IFREG | 0666;
+		stbuf->st_nlink = 1;
+		stbuf->st_size = 5;
+
 	} else if (strcmp(path, error_path) == 0) {
 		stbuf->st_mode = S_IFREG | 0444;
 		stbuf->st_nlink = 1;
@@ -212,6 +220,7 @@ static int display_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
 		filler(buf, panel_path + 1, NULL, 0);
 		filler(buf, command_path + 1, NULL, 0);
 		filler(buf, temperature_path + 1, NULL, 0);
+		filler(buf, pu_stagetime_path + 1, NULL, 0);
 		filler(buf, version_path + 1, NULL, 0);
 		filler(buf, error_path + 1, NULL, 0);
 		return 0;
@@ -233,7 +242,8 @@ static int display_open(const char *path, struct fuse_file_info *fi) {
 
 	// read-write items
 	if (strcmp(path, command_path) == 0 ||
-	    strcmp(path, temperature_path) == 0) {
+	    strcmp(path, temperature_path) == 0 ||
+	    strcmp(path, pu_stagetime_path) == 0) {
 		write_allowed = true;
 	} else if (strcmp(path, panel_path) == 0 ||
 		   strcmp(path, version_path) == 0 ||
@@ -286,7 +296,8 @@ static int display_create(const char *path, mode_t mode, struct fuse_file_info *
 	(void) fi;
 
 	if (strcmp(path, command_path) == 0 ||
-	    strcmp(path, temperature_path) == 0) {
+	    strcmp(path, temperature_path) == 0 ||
+	    strcmp(path, pu_stagetime_path) == 0) {
 		return 0;
 	}
 
@@ -308,7 +319,8 @@ static int display_create(const char *path, mode_t mode, struct fuse_file_info *
 static int display_truncate(const char *path, off_t offset) {
 	(void) offset;
 	if (strcmp(path, command_path) == 0 ||
-	    strcmp(path, temperature_path) == 0) {
+	    strcmp(path, temperature_path) == 0 ||
+	    strcmp(path, pu_stagetime_path) == 0) {
 		return 0;
 	}
 
@@ -362,6 +374,16 @@ static int display_read(const char *path, char *buffer, size_t size, off_t offse
 		char t_buffer[16];
 		int length = snprintf(t_buffer, sizeof(t_buffer), "%3d\n", t);
 		return buffer_read(buffer, size, offset, t_buffer, length, false, false);
+	} else if (strcmp(path, pu_stagetime_path) == 0) {
+		int s = pu_stagetime;
+		if (s < 50) {
+			s = 50;
+		} else if (s > 2000) {
+			s = 2000;
+		}
+		char s_buffer[16];
+		int length = snprintf(s_buffer, sizeof(s_buffer), "%4d\n", s);
+		return buffer_read(buffer, size, offset, s_buffer, length, false, false);
 	} else if (strcmp(path, error_path) == 0) {
 		const char *t_buf = error_texts[EPD_status(epd)];
 		return buffer_read(buffer, size, offset, t_buf, strlen(t_buf), false, false);
@@ -411,6 +433,15 @@ static int display_write(const char *path, const char *buffer, size_t size, off_
 			}
 		}
 		return size;
+	} else if (strcmp(path, pu_stagetime_path) == 0) {
+		if (size > 0) {
+			char *end = NULL;
+			long int s = strtol(buffer, &end, 0);
+			if (buffer != end && s >= 50 && s <= 2000) {
+				pu_stagetime = (int)s;
+			}
+		}
+		return size;
 	}
 
 	// test big/little endian
@@ -607,7 +638,15 @@ static void run_command(const char c) {
 		break;
 
 	case 'P':  // partial update with contents of display
-		EPD_set_temperature(epd, temperature);
+	case 'F':  // partial update bypassing temperature compensation for stagetime
+		if (c == 'P') {
+			EPD_set_temperature(epd, temperature);
+		}
+#if EPD_PARTIAL_AVAILABLE
+		else {
+			EPD_set_factored_stage_time(epd, pu_stagetime);
+		}
+#endif 
 		EPD_begin(epd);
 		if (EPD_OK != EPD_status(epd)) {
 			warn("EPD_begin failed");

README.md

@@ -1,7 +1,30 @@
 # gratis
-## Partial Update implementation notes, February 2016
+## Fast Update notes, July 2017
 
-This branch implements a proper partial update following the algorithm outlined
+The update rate for Partial Update is determined by the temperature dependent stage time.
+For 25 degrees C a typical max update rate for the 2.7" display is about 1.5 Hz.
+
+The stage time decreases as the measured temperature increases.
+For some applications a faster update rate can be useful.
+This can be achieved by setting the stage time directly bypassing the normal temperature
+dependent setting of the stage time.
+This is the same mechanism as used in the Pervasive Displays Windows application for the
+TI Launchpad and the EXT2 development board (http://www.pervasivedisplays.com/kits/ext2_kit).
+
+Decreasing the stage time increases the max update rate. If the stage time gets too small
+some ghosting (left overs from the previous image) will occur.
+Depending on the application some ghosting may be acceptable.
+
+This implementation uses the 'F' command to do a Fast Update using the stage time as set in
+/dev/epd/f_stage_time. 
+
+A video demonstrating the normal Partial Update and Fast Update for various stage times is
+available on YouTube.
+[![Fast Update Demo](https://img.youtube.com/vi/neGKnfJFHx4/0.jpg)](https://www.youtube.com/watch?v=neGKnfJFHx4)
+
+## Partial Update notes, February 2016
+
+This partial update implementation follows the algorithm outlined
 in the discussion of issue #19 on the repaper/gratis github repository.
 
 The original code in epd_fuse.c and V231G2/epd.c under PlatformWithOS did a full 4 cycle display update