How to use EVAL-CN0428 by I2C with a generic microcontroller?

Question

Hi to everyone here please,I'm in urgent need to use the capabilities of the EVAL-CN0428,in conjunction with an existing microcontrollor board,connected with an EVAL-M355-ARDZ-INT board. My question is: Is there a guide about how to use CN0428 with a generic microcontroller? I have the ADICUP3029 code,ADICUP3029 board and CN0428 code and board. Despite this, I'm not able to reply on my microcontroller the communication necessary to have PH,conductivity and temperature measurements. On my board an I2C port and some GPIO's are available By now I need only 1 CN0428,so there is no need of I2C address reassignement. I have experienced communication,but without properly understanding details. 
 I have found some unexpected behaviour: 1)The CN0428,by default ,acknowledges the I2C address 0x98 Changing its address with command 0x80 it still acknowledges the I2C address 0x98,is it correct? I kept low the CS pin during this operation,and I waited for 1 second,as in the ADICUP3029 example: this is my code about it SS1_LOW;
	Delay(100);
	i2c_write_data_buffer[0]=SET_I2C_ADDRESS;
	i2c_write_data_buffer[1]=new_addr; 
	hal_st=HAL_I2C_Master_Transmit(&hi2c1,old_addr, i2c_write_data_buffer, 2, 50);
	Delay(1000); /* wait for selected slave to change its address */
	SS1_HIGH; 2)Lot of communication between boards is done sending ASCII values on I2C,for example ,when requesting measuresensor by PuTTY terminal , a string is sent by ADICUP3029 to CN0428 : cmeasuresensor\r , then other strings are read by I2C reads from CN0428,they look the same of strings printed on PuTTY terminal. I am not able to relate these strings with I2C commands listed in adi_m355_gas_sensor.h 3)Still about strings,i'm able to read back in some way the welcome message: Welcome to Water Quality Demo! Sensor Site: 1! .. but I wonder how it works: If I read the I2C buffer more than necessary CN0428 pulls down(stretches?) the SCL pin,and it remains low unless I reset the CN0428,so, what tells to I2C master how long is the message to be read? 4)It looks that long delays are necessary between reset and some operations,is there a list of these timings?I mean without searching them one by one in ADICUP3029 CN0428 example code? Actually the code is small ,but I would like to be shure to respect all the timings and dont miss anyone. Thanks for your help or your attention. Diego Colombo Milan,Italy.

ScottH · Accepted Answer

Hello Diego, 
 Sorry for the delay. I just wanted to add a little bit about the I2C addressing in this project. 
 
 "The CN0428,by default ,acknowledges the I2C address 0x98 Changing its address with command 0x80 it still acknowledges the I2C address 0x98,is it correct?" 
 
 The default I2C address used by the ADuCM355 in the CN0428 project is 0x4C (7-bit address value, so left-shifted by 1 will give you the 0x98). The ADICUP3029 uses that address as a general call for avoiding potential I2C address conflicts. 0x4C is treated as write-only by the ADICUP3029 since all sensor board nodes are listening to that address simultaneously. 
 At start-up, the ADICUP3029 attempts to assign new I2C addresses to each of the 4 sites. It does this by holding a GPIO low for the site it would like to address and then sending an address change request command to 0x4C. All ADuCM355's on the bus will see the command, but the ADuCM355 only changes its address if it sees that GPIO is low, otherwise the request is ignored. Finally, ADICUP3029 checks for a response from the new address to see if an actual sensor was found. Then it reports which sites and which new addresses gave a response. 
 Thanks to a feature of the ADuCM355 that allows it to respond to two different I2C addresses, the sensor nodes are still listening on 0x4C even after being assigned new addresses on initialization. This is mainly for reset behavior, so if a reset was issued to the ADICUP3029, it can go through initialization like normal even if each ADuCM355 was not reset. Therefore the behavior you described is expected for the system. 
 I hope this helps. Thanks, Scott)

	Setup Write to ['20']
	a
	Setup Read to ['21']
	0' + NAK	no
	Setup Write to ['20']
	a
	Setup Read to ['21']
	0' + NAK	no
	Setup Write to ['20']
	a
	Setup Read to ['21']
	22' + NAK	Yes,22 chars
	Setup Write to ['20']
	c
Count of chars	Setup Read to ['21']
1	T
2	e
3	m
4	p
5	e
6	r
7	a
8	t
9	u
10	r
11	e
12	:
13	'
14	0
15	8
16	4
17	.
18	3
19	5
20	1
21	\r
22	\n + NAK
	Setup Write to ['20']
	a
	Setup Read to ['21']
	0' + NAK	no
	Setup Write to ['20']
	a
	Setup Read to ['21']
	16' + NAK	Yes,16 chars
	Setup Write to ['20']
	c
Count of chars	Setup Read to ['21']
1	p
2	H
3	:
4	'
5	1
6	3
7	.
8	2
9	4
10	3
11	5
12	\r
13	\n
14	\r
15	\n
16	~ + NAK
	Setup Write to ['20']
	a
	Setup Read to ['21']
	0' + NAK