how can I redraw only the rectangle in my app - c

Question

I'm using Visual Studios Win32 to develop a control app for an ARINC 629 bus. It works fine for an event-driven action such as a mouse click, but I need it to update in real-time when I'm receiving data over the ARINC 629 bus.
I've learned that Win32 is not the best environment for graphics that need to be continuously updated, but my app is working fairly well except for some flicker.
It seems most of the suggestions on how to reduce flicker don't address when a function is called continuously.
Double-buffering does not seem to help much.
In this case, if I could just redraw the rectangle and not the entire client area, I could reduce or eliminate the flicker.
Here is a code snippet:
void twirling_baton_left_channel(HDC hdc, HWND hWnd, unsigned int left_chan_data_receive)
{
LPRECT lpRect;
RECT rect_chan_one;
lpRect = &rect_chan_one;
lpRect->left = 0;
lpRect->top = 0;
lpRect->right = 0x01ba;
lpRect->bottom = 0x01c6;
static unsigned int wait_to_redraw_left_chan = 0;
status_baton_one.left = 0xb2;
status_baton_one.top = 0x28;
status_baton_one.right = 0x11c;
status_baton_one.bottom = 0x4b;
/* draw the running indicator */
if(wait_to_redraw_left_chan > 5)
{
RedrawWindow(hWnd, lpRect, NULL, RDW_INVALIDATE); //RedrawWindow((HWND)hdc, NULL, NULL, RDW_ERASE);
wait_to_redraw_left_chan = 0;
}
wait_to_redraw_left_chan++;
//SelectObject(ps.hdc, GetStockObject(DC_BRUSH));
if(left_chan_data_txrx)
{
SetDCBrushColor(hdc, RGB(0, 255, 0)); // green
Rectangle(hdc, status_baton_one.left, status_baton_one.top, status_baton_one.left+30, status_baton_one.top+20);
}
else
{
SetDCBrushColor(hdc, RGB(128,128,128)); //grey
Rectangle(hdc, status_baton_one.left, status_baton_one.top, status_baton_one.left+30, status_baton_one.top+20);
}
}
I'm trying to use the RedrawWindow() command to only redraw the box defined by the 'Rectangle' function, but it causes the entire client area to be redrawn, which causes a flicker since it is being called continuously.