NAME

k8055m_flush, k8055m_set_auto_flush, k8055m_get_auto_flush -- k8055-pic18f HID protocol auto flush feature

LIBRARY

k8055-pic18f access library

SYNOPSIS

#include "k8055m.h"

int
k8055m_flush(int cardNumber);

int
k8055m_set_auto_flush(int cardNumber, int flag);

int
k8055m_get_auto_flush(int cardNumber);
    

DESCRIPTION

The k8055-pic18f board uses the USB HID protocol, to communicate with the host computer. This imposes a limit of 1000 command messages per second. Rapid changes in output states can therefore cause an IO bottleneck.

The k8055-pic18f access library maintains an in-memory status of what a connected card's output ports "should" currently look like. All output related functions will modify that data. k8055m_flush() will transmit that new status to the card in an actual HID command message. If the auto-flush feature is enabled (which it is by default), then every call to an output function will cause an implicit call to k8055m_flush().

To optimize the response time of the k8055-pic18f, a program should either use k8055m_set_output() to cause all desired changes at once, or turn off the auto-flush feature, call multiple output functions, then call k8055m_flush() to execute them.