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Renesas FS2012 + PIC16F877A I2C Issues

 
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welbertdeoliveira



Joined: 29 Aug 2022
Posts: 1

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Renesas FS2012 + PIC16F877A I2C Issues
PostPosted: Mon Aug 29, 2022 11:32 am     Reply with quote

Good afternoon.

I'm facing some problems for interface a Renesas FS2012 gas flow sensor with a PIC16F877A. The procedure for configuring the communication, based on the documentation is:

"To obtain data from the sensor, send START bit, slave address (0x07) and read bit (READ) to FS2012 and then read the two bytes of sensor data." (https://www.renesas.com/us/en/document/apn/fs2012-sample-application?language=en, page 10, "3.2 Sensor Functions").

I'm trying to configure the interface and obtain the MSB and LSB, and print on a 16x2 LCD. But, it's only possible to see FFh in both registers.

I can see the I2C protocol working by an oscilloscope.

Could anyone help me?

Best regards.
Code:

/*
-------------------------------------------------------------------------------------
   Renesas FS2012 Gas Flow Sensor + display LCD 16x2
   Biblioteca nativa do CCS C
   Modo 4 bits
   I/O no PortD

   Conexoes fĂ­sicas do LCD na PortD

   lcd_enable_pin    pin_B5
   lcd_rs_pin        pin_B4
   lcd_rw_pin        pin_B3
   lcd_data4         pin_D4
   lcd_data5         pin_D5
   lcd_data6         pin_D6
   lcd_data7         pin_D7

-------------------------------------------------------------------------------------
*/

#include    <16F877A.h>
#use        delay(clock = 4000000)
#use        I2C(master, fast = 100000, sda = pin_C4, scl = pin_C3)
#fuses      XT, NOWDT, PUT, NOLVP

#define   lcd_rs_pin        pin_B5
#define   lcd_rw_pin        pin_B4
#define   lcd_enable_pin    pin_B3
#define   lcd_data4         pin_D4
#define   lcd_data5         pin_D5
#define   lcd_data6         pin_D6
#define   lcd_data7         pin_D7
#define   sensor_address    0x07


#include    <lcd.c>

unsigned int8 dado_H, dado_L = 0;

void main()
{

   // Habilita o LCD e imprime mensagens iniciais
   lcd_init();
   lcd_putc('\f');
   delay_ms(100);
         
  while(true)
   {
   
   i2c_start();
   i2c_write(sensor_address);
   i2c_write(1);
   i2c_start();
   i2c_write(sensor_address);
   dado_H = i2c_read(1);
   dado_L = i2c_read(0);
   i2c_stop();
   
   lcd_gotoxy(1,1);
   lcd_putc("MSB: ");
   lcd_gotoxy(6,1);
   printf(lcd_putc, "%X", dado_H);
   lcd_gotoxy(1,2);
   lcd_putc("LSB: ");
   lcd_gotoxy(6,2);
   printf(lcd_putc, "%X", dado_L);

   }
}
PCM programmer



Joined: 06 Sep 2003
Posts: 21674

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PostPosted: Mon Aug 29, 2022 3:17 pm     Reply with quote

The FS2012 data sheet lists 0x07 as the slave address. That's in 7-bit format.
However, CCS i2c routines use 8-bit format, so double that to 0x0E.
Then we get:

i2c read address: 0x0E
i2c write address: 0x0F

--------------------------------------
Also, your i2c read data routine needs to be changed to this:
Quote:
i2c_start();
i2c_write(SENSOR_WRITE_ADDRESS); // 0x0F
i2c_write(1);
i2c_start();
i2c_write(SENSOR_READ_ADDRESS); // 0x0E
dado_H = i2c_read(1);
dado_L = i2c_read(0);
i2c_stop();
Ttelmah



Joined: 11 Mar 2010
Posts: 18225

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PostPosted: Wed Aug 31, 2022 1:24 am     Reply with quote

It is slightly worrying that the device is using a reserved address.

In 7bit addresses 0 to 7, and 78 to 7F are legally reserved addresses.
Devices are not meant to use these. 7 is actually reserved as the speed
control address value.
The I2C valid 7bit device addresses are 8 to 77.
That a device is being sold that uses one of the reserved addresses, is
'scary'... Sad
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