Reading Exposure Time from Sensing ISX031

Overview

• Ensure the ISX031 module you have is using either the MAX9295 or MAX96717 serializer. By default, the Sensing ISX031 uses the MAX9295 for 60 FPS mode, while the mainstream ISX031 modules are based on the MAX96717 and operate at 30 FPS.

• Use the MAX9295’s (or MAX96717) I²C translation feature to map each ISX031 from the default address (0x1A) to a unique address.

• Implement a background program to monitor the latest Frame ID and Exposure Time.

MAX9295 or MAX96717

Add the following code during initMAX9296:

## MAX96717 + MAX9296 _ 3Gbps GMSL2 Receiver Rate
i2ctransfer -f -y 2 w3@$MAX9296 0x00 0x01 0x01

## MAX9295 + MAX9296 _ 6Gbps GMSL2 Receiver Rate
i2ctransfer -f -y 2 w3@$MAX9296 0x00 0x01 0x02    

I2C Translation

Add the following code during initMAX9295 when only link A or only link B of the MAX9296 is enabled.

## $SER = Serialzier, could be MAX9295 or MAX96717
## Using Bus 2 as 
SER_A=0x76
SER_B=0x77
ISX031_PRIME=0x1a
ISX031_A=0x16
ISX031_B=0x17

## sudo i2cdetect -r -y 2
##      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
## 00:                         -- -- -- -- -- -- -- --
## 10: -- -- -- -- -- -- -- -- -- -- 1a -- -- -- -- --
## 20: -- -- -- -- -- -- -- -- 28 29 -- -- -- -- -- --
## 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
## 40: -- -- -- -- -- -- -- -- 48 -- 4a -- -- -- -- --
## 50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
## 60: -- -- -- -- -- -- -- -- 68 -- -- -- 6c -- -- --
## 70: -- -- -- -- -- -- 76 --

## When MAXM9295 Link A is enabled
## Using MAX9295 I2C SRC_B and I2C DST_B
sudo i2ctransfer -f -y 2 w3@$SER_A 0x00 0x42 $(($ISX031_A*2))
sudo i2ctransfer -f -y 2 w3@$SER_A 0x00 0x43 $(($ISX031_PRIME*2))

## sudo i2cdetect -r -y 2
##      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
## 00:                         -- -- -- -- -- -- -- --
## 10: -- -- -- -- -- -- -- -- -- -- 1a -- -- -- -- --
## 20: -- -- -- -- -- -- -- -- 28 29 -- -- -- -- -- --
## 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
## 40: -- -- -- -- -- -- -- -- 48 -- 4a -- -- -- -- --
## 50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
## 60: -- -- -- -- -- -- -- -- 68 -- -- -- 6c -- -- --
## 70: -- -- -- -- -- -- 76 --

...

## When MAXM9295 Link B is enabled
## Using MAX9295 I2C SRC_B and I2C DST_B
sudo i2ctransfer -f -y 2 w3@$SER_B 0x00 0x42 $(($ISX031_A*2))
sudo i2ctransfer -f -y 2 w3@$SER_B 0x00 0x43 $(($ISX031_PRIME*2))

A Background Script to Read Frame Count and Exposure Time

The following sample code is for demonstration purposes. The same concept can be implemented in C++ to achieve a much faster response.

#!/bin/bash

ISX031_A=0x1A
F_ID=0
PREV_FRAME_COUNT=0

while true; do
    # Get Frame Count as an unique ID fro comparison
    FRAME_COUNT=$(sudo i2ctransfer -f -y 2 w2@$ISX031_A 0x7D 0xC8 r4)        

    if [ "$PREV_FRAME_COUNT" = "$FRAME_COUNT" ]; then        
        continue
    else                
         ((F_ID++))
        PREV_FRAME_COUNT=$FRAME_COUNT
    fi

    # Get Exposure Time
    EXP_LOW=$(sudo i2ctransfer -f -y 2 w2@$ISX031_A 0x62 0x28 r1)
    EXP_HIGH=$(sudo i2ctransfer -f -y 2 w2@$ISX031_A 0x62 0x29 r1)
    EXP_HEX="0x${EXP_HIGH#0x}${EXP_LOW#0x}"
    EXP_DEC=$((EXP_HEX))    

    # Get Current Epoch in us
    us=$(date +%s%6N)
    printf "[$us] Frame Count:$F_ID Exposure Time:${EXP_DEC}us \n"  
done

An example output is as follows:

[1765181380695635] Frame Count:224 Exposure Time:12209us 
[1765181380732334] Frame Count:225 Exposure Time:12732us 
[1765181380768965] Frame Count:226 Exposure Time:12998us 
[1765181380805567] Frame Count:227 Exposure Time:13540us 
[1765181380842203] Frame Count:228 Exposure Time:13570us 
[1765181380878771] Frame Count:229 Exposure Time:13904us 
[1765181380915170] Frame Count:230 Exposure Time:14209us 
[1765181380951825] Frame Count:231 Exposure Time:14514us 
[1765181380988603] Frame Count:232 Exposure Time:14838us 
[1765181381025247] Frame Count:233 Exposure Time:14990us 
[1765181381061794] Frame Count:234 Exposure Time:14666us 
[1765181381098312] Frame Count:235 Exposure Time:14361us 
[1765181381135413] Frame Count:236 Exposure Time:14095us 
[1765181381172085] Frame Count:237 Exposure Time:14484us 
[1765181381208689] Frame Count:238 Exposure Time:15045us 
[1765181381245395] Frame Count:239 Exposure Time:15180us 
[1765181381281944] Frame Count:240 Exposure Time:15504us 
[1765181381318557] Frame Count:241 Exposure Time:15847us 
[1765181381355241] Frame Count:242 Exposure Time:16190us 
[1765181381391773] Frame Count:243 Exposure Time:16552us 
[1765181381428398] Frame Count:244 Exposure Time:16914us 
[1765181381464928] Frame Count:245 Exposure Time:17276us 
[1765181381501462] Frame Count:246 Exposure Time:16914us 
[1765181381538022] Frame Count:247 Exposure Time:16296us 
[1765181381574590] Frame Count:248 Exposure Time:15678us 
[1765181381611065] Frame Count:249 Exposure Time:15591us 
[1765181381647962] Frame Count:250 Exposure Time:15180us 
[1765181381685820] Frame Count:251 Exposure Time:14857us 
[1765181381723562] Frame Count:252 Exposure Time:14533us 
[1765181381760362] Frame Count:253 Exposure Time:14228us 
[1765181381797167] Frame Count:254 Exposure Time:13923us 
[1765181381833968] Frame Count:255 Exposure Time:13875us 
[1765181381870742] Frame Count:256 Exposure Time:14179us 
[1765181381907463] Frame Count:257 Exposure Time:14484us 
[1765181381944374] Frame Count:258 Exposure Time:14857us 
[1765181381980958] Frame Count:259 Exposure Time:15180us 
[1765181382017483] Frame Count:260 Exposure Time:15504us 
[1765181382054503] Frame Count:261 Exposure Time:21028us 
[1765181382091385] Frame Count:262 Exposure Time:25695us 
[1765181382128931] Frame Count:263 Exposure Time:26895us 
[1765181382166195] Frame Count:264 Exposure Time:25314us 
[1765181382202607] Frame Count:265 Exposure Time:22400us 
[1765181382239446] Frame Count:266 Exposure Time:18857us 
[1765181382276323] Frame Count:267 Exposure Time:15295us 
[1765181382312749] Frame Count:268 Exposure Time:12247us 
[1765181382349261] Frame Count:269 Exposure Time:10000us