Zeptel specification

Can any one help me to disign new hardware driver that can directly talk with zap channel.
I need specification of zap channel . I have gone through chan_zap. c but not able to find how exacly it communicate . Actually We have our own telephone adaptor that listen trigger from basic telephone and convert then into event messages (not sip) . now I want to map these event messages to zap chan events . We are running asterisk on same hardware on which triggers are comming .