Requirements/Analysis/Limitations

Code Size in current implementation:
+Read off from Kiel compiler output listing
+Badge: 362 bytes < 20 KByte on Atmel 
+Door Module: 1130 bytes < 32 KBytes SRAM on XS-40


2 sec. requirement: 
+seems reasonable
+sonar: 0.7 sec
+RF send and receive: 2 ms + 1.7 ms + 2 ms
++RS 232 and RF baud rates, packet sizes
++bad if strong interference (8 retries with up to 360ms of random delay between retries)
+FPGA: can finish checking in about 4 clock cycles @25MHz, 
+code in microcontroller take only milliseconds


using only 1 sonar:
+aiming directly in front of the door, assuming user walks directly towards the door 


power consumption:
+Calculated from specifications
+Badge:
++Atmel:
++RF:
++ will try running 8051 off the batteries on the RF board
+Door Module:
++XS-40
++Sonar kit
+++decoupling Cap