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A device driver of CCS811-Air quality sensor for AVR. This code is a part of pAVRlib.
Requirement
-
twi-controller.asm (a part of pAVRlib)
-
wait.asm (a part of pAVRlib)
Subroutines
void CCS811_RESET() (in: (none), out: (none))
resets CCS811 (via nRESET).
To use this routine, you need to define CCS811_USE_RESET.
To define the pin for nRESET, use CCS811_RESET_DDR, CCS811_RESET_PORT and CCS811_RESET_PINNUM.
For example, to use PB6-pin for nRESET:
.define CCS811_USE_RESET
.equ CCS811_RESET_DDR = DDRB
.equ CCS811_RESET_PORT = PORTB
.equ CCS811_RESET_PINNUM = 6
char CCS811_SEARCH() (in: (none), out: r24)
This routine searches CCS811. This routine returns r24 < 0x80 (positive value as a signed char) as the address of CCS811, or r24 $\ge$ 0x80 (negative value as a signed char) if CCS811 is not found.
Known Issues
-
Error handling of I²C is not complete.
-
Only one device can be found.
char CCS811_INITIALIZE(addr) (in: r24, out: r24)
initializes CCS811.
addr (r24) is a I²C-Address of CCS811.
It returns a status value (r24) as a result.
Initialize is succeeded if r24 = 0. r24 = -1 (0xff) means "no valid application" (see datasheet of CCS811 for more details of "application"). r24 = -2 (0xfe) means "invalid firmware mode".
unsigned int CCS811_WRITE(char addr, char ccs811_reg, char bytes, char *data)
writes data to CCS811. For example, the data in r0, r1, … will be sent if you call this routine with r19:r18 = 0,
in
| r24 | I²C-Address of CCS811 |
| r22 | Register of CCS811 to write |
| r20 | the number of bytes to write |
| r19:r18 | start address of data to be sent |
out
| r25 | TWI status |
| r24 | (unchanged) |
unsigned int CCS811_READ(char addr, char ccs811_reg, char bytes, char *data)
reads data from CCS811. For example, the received data will be stored in r0, r1, … if you call this routine with r19:r18 = 0.
in
| r24 | I²C-Address of CCS811 |
| r22 | Register of CCS811 to read |
| r20 | the number of bytes to read |
| r19:r18 | start address of data to be stored |
out
| r25 | TWI status |
| r24 | (unchanged) |
See also
Examples
The following programs reads data from CCS811 and show the received data.
../examples/ccs811-test.asm
The test program for ccs811-asm (asm version).
This program reads data from CCS811 and show the received data via USART like this:
$ dterm /dev/ttyUSB0 4800
# Hallo CCS811
# CCS811 found at 0x5A
# Waiting for the first data ....
# Entering interrupt mode
eCO2: 406 ppm, eTVOC: 0 ppb [ 01 96 00 00 98 00 07 23 ]
eCO2: 409 ppm, eTVOC: 1 ppb [ 01 99 00 01 98 00 07 21 ]
eCO2: 413 ppm, eTVOC: 1 ppb [ 01 9D 00 01 98 00 07 20 ]
eCO2: 413 ppm, eTVOC: 1 ppb [ 01 9D 00 01 98 00 07 20 ]
eCO2: 406 ppm, eTVOC: 0 ppb [ 01 96 00 00 98 00 07 23 ]
eCO2: 408 ppm, eTVOC: 1 ppb [ 01 98 00 01 98 00 07 22 ]
:
:To compile this file, the following files are required (These files are parts of the pAVRlib).
See also: examples/README.org
../examples-C/ccs811-test.c
The test program for ccs811.asm (C version).
To compile this file, the following files are required (These files are parts of the pAVRlib).
See also: examples-C/README.org