pmarks-net

Xfinity XB3 hardware mod: Disable WiFi and save 2 watts

Background

Comcast has a prepaid "Xfinity NOW" service that's cheaper than normal Xfinity, with unlimited data instead of a 1.2TB/month cap. If you currently have Xfinity, the NOW online signup is hidden, but when I called to cancel my Xfinity service on a date a couple weeks in the future, the NOW signup started working immediately. (I initially queried a neighbor's address to confirm that NOW was available in my area.)

The catch is that you can't use your own modem. They provide a free Arris TG1682P (also known as the XB3), but it's huge and uses more power (14.9 watts) than my Arris SB8200 (9.8 watts). I suspect they retired millions of these things and treat NOW as a recycling service.

The XB3 lets you enable bridge mode via the admin page at http://10.0.0.1/, and IPv4/IPv6 works just like a plain modem, but even in bridge mode, the gateway broadcasts several hidden SSIDs with no option to disable the radios. Curiously I did not see an `xf

madex

char *itoaFixedWidth(int32_t zahl) {
   static uint32_t subtractors[] = {1000000000, 100000000, 10000000, 1000000,
                                    100000, 10000, 1000, 100, 10, 1};
   static char string[12];
   char n, *str = string, sign = zahl < 0 ? '-' : ' ';	
   uint32_t *sub = subtractors;
   uint32_t u = zahl < 0 ? (uint32_t) -zahl : (uint32_t) zahl;    
   uint8_t  i = 10;	
   *str++ = ' ';
   while (i > 1 && u < *sub) {