Dave Ball wrote: > I've had a first stab at schematics for the Telit modem. Comments, > feedback, abuse all welcome :-) >
Do we need the transistors Q8101/Q8102? Telit mentioned that an open collector output is required but I'm not sure if the GPIOs of the CPU are Hi-Z outputs or can be switched into this state. However the PMU's GPIO lines are all open drain outputs so there we wouldn't need them. I think the current should not be a big problem for the GPIOs because Telit specifies the max current on MODEM_ON is limited to 100uA. > Noted missing is the antenna circuit. Is the external antenna > connection something we want for gta02-core? I know I'll not use it, > but I guess others might? Also, I was hoping someone else might want to > have a look at the RF bits - I've no idea what's appropriate here, and > me guessing probably isn't the best approach! Any takers? > If we only use one internal antenna, the antenna circuit doesn't require any additional components (assumed antenna Zin=50Ohm). The only requirement is that the antenna is connected through a plain 50 Ohm transmission line with less than 0.3dB loss. What type of antenna are we going to use, is it a commercially available one? Rene _______________________________________________ gta02-core mailing list [email protected] https://lists.openmoko.org/mailman/listinfo/gta02-core
