Driver for accelerometer LSM303DLHC

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ales.coppelli
Posts: 26
Joined: Wed Aug 08, 2018 9:15 am

Driver for accelerometer LSM303DLHC

Post by ales.coppelli » Sat Dec 19, 2020 11:25 am

Hi to all.
I'm trying to development a simple lsm303dhlc accelerometer driver
using the I2C class already present in Micropython
( I have a STM32F411 Discovery board and the lsm303dhlc accelerometer is
hard linked to the PB6(scl) and PB9(sda) board pin).

Scenario ( about use a I2C class in my new accelerometer class):
------------------------------------------------------------------------------------

I wrote my new ( simple ) accelerometer class like:

typedef struct _accelerometer_lsm303dlhc_obj_t {
mp_obj_base_t base;
struct machine_hard_i2c_obj_t* i2c;
union _accel_x{
uint8_t low;
uint8_t high;
int16_t value;
}accel_x;
} accelerometer_lsm303dlhc_obj_t;

I would like to use the already present I2C class in Micropython
and so I prepare the field "struct machine_hard_i2c_obj_t* i2c"
in the accelerometer struct.

When I try to use the method "machine_i2c_writeto_mem()" there are compilation problems
( I tried different solutions but I haven't understood where I'm wrong ).


I saw that in "ports/stm32/machine_i2c.c" there is the definition of
I2C class ( hard and soft ).
Then the class's methods are in the 'mp_machine_soft_i2c_locals_dict' table.
( line 276 in "ports/stm32/machine_i2c.c").
The array/table 'mp_machine_soft_i2c_locals_dict_table[]' is in
"extmod/machine_i2c.c" ( line 635-655).
( so something I2C stuff are in "ports/stm32/machine_i2c.c" and something else in "extmod/machine_i2c.c" )

Question ( about how to link to use a external class's method ):
---------------------------------------------------------------

I would ( or better I have to ) use the I2C methods
"machine_i2c_readfrom_mem()" and "machine_i2c_writeto_mem()".
( these functions are declared and defined in "extmod/machine_i2c.c" not in "ports/stm32/machine_i2c.c" )

I would like to write sentence like these:

self->i2c->machine_i2c_writeto_mem(bla_bla);
or
self->i2c->machine_i2c_readfrom_mem(bla_bla);

How to link, from my class, these two functions ?

(a) #include "extmod/machine_i2c.h" doesn't work
(b) maybe something in my custom new project class 'micropython.mk'
(c) peraphs with a "extern" directive in my class file

Ale

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