From 00de7d00ab74c3a7e3b0df01cd4b448ff4dfaa31 Mon Sep 17 00:00:00 2001
From: dchvs <daniel.chaves@ridgerun.com>
Date: Thu, 4 Mar 2021 00:34:39 -0600
Subject: [PATCH] documentation: Update README with AE

---
 README.md | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 0e8689c..19dc4b2 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ gst-launch-1.0 nvarguscamerasrc sensor-id=0 aelock=true awblock=true ! 'video/x-
 ### UDP Streaming Test
 #### Sender Endpoint
 ```
-gst-launch-1.0 nvarguscamerasrc ! 'video/x-raw(memory:NVMM), width=(int)1280, height=(int)720, format=(string)NV12,framerate=(fraction)30/1' ! omxh264enc control-rate=2 bitrate=8000000 ! 'video/x-h264, stream-format=(string)byte-stream' ! h264parse ! rtph264pay mtu=1400 ! udpsink host=$HOST_IP port=5000 sync=false async=false
+gst-launch-1.0 nvarguscamerasrc ! 'video/x-raw(memory:NVMM), width=(int)1280, height=(int)720, format=(string)NV12,framerate=(fraction)60/1' ! omxh264enc control-rate=2 bitrate=8000000 ! 'video/x-h264, stream-format=(string)byte-stream' ! h264parse ! rtph264pay mtu=1400 ! udpsink host=$HOST_IP port=5000 sync=false async=false
 ```
 
 #### Receiver Endpoint
@@ -71,11 +71,58 @@ v4l2-ctl -d /dev/video0 --set-fmt-video=width=1280,height=720,pixelformat=RG12 -
 
 #### Slave
 ```
-v4l2-ctl -d /dev/video01 --set-fmt-video=width=1280,height=720,pixelformat=RG12 --set-ctrl bypass_mode=0 --stream-mmap
+v4l2-ctl -d /dev/video1 --set-fmt-video=width=1280,height=720,pixelformat=RG12 --set-ctrl bypass_mode=0 --stream-mmap
+```
+
+### AE Synchronized
+First run the master pipeline and then the slave pipeline:
+
+#### Master Pipeline
+```
+gst-launch-1.0 nvarguscamerasrc sensor-id=1 ! 'video/x-raw(memory:NVMM), width=(int)1280, height=(int)720, format=(string)NV12,framerate=(fraction)60/1' ! fakesink
+```
+
+#### Slave Pipeline
+```
+gst-launch-1.0 nvarguscamerasrc sensor-id=0 aelock=true awblock=true ! 'video/x-raw(memory:NVMM), width=(int)1280, height=(int)720, format=(string)NV12,framerate=(fraction)60/1' ! fakesink
+```
+
+### Run script
+```
+./script_to_control_gain_exposure.sh &
 ```
 
 ## Appends
 
+#### Auto Exposure
+
+The AE controls realays in the feedback provided by the Driver's camera sensor to the nvarguscamerasrc libraries,
+and the custom DTSIs with the sensor parameters definitions.
+As the AE has interdependency with the digital gain. This gain it's and operation on the Driver, and follows this setup:
+
+```bash
+  /*
+   * Digital gain equation:
+   *
+   *  RANGE: 1x, 7.97x
+   *  GAIN: VAL / STEPS;
+   *  STEPS: 1/32
+   *
+   *  SCALE FACTOR = 100.000
+   *
+   *  min_gain_val = 100.000
+   *  max_gain_val = 797.000
+   *  step_gain_val = 3125
+   */
+
+   MT9M021 sensor datasheet:
+   * <a href="https://files.niemo.de/aptina_pdfs/MT9M021-M031_Developer_Guide.pdf">MT9M021 Developer Guide</a>
+```
+
+Where, the min_gain_val, max_gain_val, step_gain_val are part of the cameras' DTSI (tegra186-tx2-spiri-camera.dtsi) fixed parameters
+as per the datasheet. The step_gain_val consists of the steps (1/32 for the register) scaled to a value that makes this fraction become an significant
+in integer.
+
 #### Kernel Changes
 
 The Driver for the MT9M021 cameras consists on the following structure, that adds the DTB and Kernel sources, along with its Makefiles that lead its portability to a Kernel source.