Hi,
I am trying to develop a high speed application using the nRF51822 chipset. As part of my application, I need to send at least 125 HID IN reports (each 20 bytes long) to the central device. The BLE parameters on my peripheral device ( nRF51822) are as follows:
MIN_CONN_INTERVAL = 7.5 ms
MAX_CONN_INTERVAL = 15 ms
SLAVE_LATENCY = 20
I am sending custom HID IN reports using an infinite loop in the main function as follows:
for (;;)
{
app_sched_execute();
power_manage();
mouse_movement_send(2000,2000);
nrf_delay_ms(<delay_in_ms>);
}
I am using the nrf_delay_ms() function to vary the delay (i.e, the number of HID IN reports per second).
On Windows 10, I am able to receive data reliably upto a delay of 50 ms (approx 20 reports a second). For a delay lesser than 50 ms, the BLE connection seems to drop at times or it shows CONNECTED on my PC but the ble_hids_inp_rep_send() returns an error code of NRF_ERROR_INVALID_STATE . The net effect is that I am unable to receive even a single HID report on the PC.
However, with MacOS, I am able to reliably receive data upto 15ms delay ( approx 65 reports a second) after which the connection becomes unstable and it stops entirely at a delay of about 10 ms( approx 100 reports a second).
Below is the code on my PC which I use to read input reports (using HIDAPI library):
hid_device *handle = NULL;
handle = hid_open(VENDOR_ID, PRODUCT_ID, 0, usage, 0);
int ret;
cout << "Reading data from HID device..\n";
do
{
ret = hid_read(handle, read_buf, report_length);
cout << "Reading data from HID device.. ret: "<<ret<<" \n";
}while(ret == 0);
Could anyone explain the reason of such behavior? And how can I achieve higher speeds on both the platforms ?
Regards
Mustafa
