BLE Driver Unable to write to a characteristic

RE: BLE Driver Unable to write to a characteristic

RK — Sun, 19 Jul 2015 08:04:35 GMT

nope can't help you with that code, don't use the python stuff. At least you found the correct handle now.

RE: BLE Driver Unable to write to a characteristic

carvalhn — Sun, 19 Jul 2015 07:34:50 GMT

The handle appears different as I have changed the order of the characteristics in the code.

It appears the handle for Characteristic A102 is 0x0015 . I am still unable to write to it with the do_write function specified here devzone.nordicsemi.com/.../ .

hrm_ctl_handle is 0x0015

def do_write(self,value):

 global hrm_ctl_handle

    print "do_write",type(value),value,"-",hrm_ctl_handle

    led_value = [value]

    led_array = util.list_to_uint8_array(led_value)

    write_params = ble_driver.ble_gattc_write_params_t()

    write_params.handle = hrm_ctl_handle

    write_params.len = 1

    write_params.p_value = led_array.cast()

    write_params.write_op = ble_driver.BLE_GATT_OP_WRITE_REQ

    write_params.offset = 0

Could you please help me?

Thanks and Regards, Neil

RE: BLE Driver Unable to write to a characteristic

carvalhn — Sun, 19 Jul 2015 07:31:28 GMT

Ok I have done created a new method and manually specified the start handle for the descriptor discovery service.

Received descriptor discovery response, descriptor count: 5

on Discovery response Handle: 0x000D, UUID: 0x2803

on Discovery response Handle: 0x000E, UUID: 0xA101

on Discovery response Handle: 0x000F, UUID: 0x2902

on Discovery response Handle: 0x0010, UUID: 0x2803

on Discovery response Handle: 0x0011, UUID: 0x2A38

Press enter to toggle notifications 1

Discovering descriptorsvjhghgjh

Received descriptor discovery response, descriptor count: 5

on Discovery response Handle: 0x0011, UUID: 0x2A38

on Discovery response Handle: 0x0012, UUID: 0x2803

on Discovery response Handle: 0x0013, UUID: 0xA103

on Discovery response Handle: 0x0014, UUID: 0x2803

on Discovery response Handle: 0x0015, UUID: 0xA102

RE: BLE Driver Unable to write to a characteristic

RK — Sun, 19 Jul 2015 06:59:06 GMT

Why didn't it work? Error message? What? If you can't discover the descriptors then there's something wrong. The service says descriptors go to 0x15, you need to work out how to get them all, perhaps you will then find your error.

RE: BLE Driver Unable to write to a characteristic

carvalhn — Sun, 19 Jul 2015 06:52:31 GMT

Hi rk

Thanks for your response

I had issued a second char discovery but that did not work

For the writing to a characteristic part, I have written to the correct handle which is 11 in this scenario but It still doesnt write properly

I m able to write to a descriptor but not to a characteristic , I m confused why

Could you please help?

Thanks and Regards Neil

RE: BLE Driver Unable to write to a characteristic

RK — Sun, 19 Jul 2015 03:00:59 GMT

You haven't discovered all the characteristics. The service discovery shows handles all the way up to 0x0015. You've only discovered up to 0x0011. You need to do another discover descriptors starting at 0x0012 until you've exhausted the service. The payload for the underlying ATT find information request is of max size MTU-2, which is 21 bytes, which is 5 {Handle,value} pairs.