Added CP2104 USB to UART bridge

library/silabs.dcm

@@ -1,5 +1,11 @@
 EESchema-DOCLIB  Version 2.0
 #
+$CMP CP2104
+D Single-Chip USB-to-UART Bridge, USB 2.0 Full-Speed, 2Mbps UART, QFN package
+K uart usb bridge interface transceiver
+F https://www.silabs.com/Support%20Documents/TechnicalDocs/cp2104.pdf
+$ENDCMP
+#
 $CMP CP2112
 D HID USB to SMBUS master bridge
 K USB SMBUS bridge

library/silabs.lib

@@ -1,6 +1,46 @@
 EESchema-LIBRARY Version 2.3
 #encoding utf-8
 #
+# CP2104
+#
+DEF CP2104 U 0 40 Y Y 1 F N
+F0 "U" 300 1050 50 H V L CNN
+F1 "CP2104" 300 950 50 H V L CNN
+F2 "Housings_DFN_QFN:QFN-24-1EP_4x4mm_Pitch0.5mm" 300 850 50 H I L CNN
+F3 "" -550 1250 50 H I C CNN
+$FPLIST
+ QFN*4x4mm*Pitch0.5mm*
+$ENDFPLIST
+DRAW
+S -600 800 600 -900 0 1 10 f
+X RI 1 700 600 100 L 50 50 1 1 I
+X GND 2 0 -1000 100 U 50 50 1 1 W
+X D+ 3 -700 100 100 R 50 50 1 1 B
+X D- 4 -700 0 100 R 50 50 1 1 B
+X VIO 5 -200 900 100 D 50 50 1 1 W
+X VDD 6 0 900 100 D 50 50 1 1 W
+X REGIN 7 -700 600 100 R 50 50 1 1 W
+X VBUS 8 -700 400 100 R 50 50 1 1 I
+X ~RST 9 700 -500 100 L 50 50 1 1 B
+X NC 10 200 900 100 D 50 50 1 1 P
+X RXD 20 700 0 100 L 50 50 1 1 I
+X GPIO.3 11 -700 -500 100 R 50 50 1 1 B
+X TXD 21 700 100 100 L 50 50 1 1 O
+X GPIO.2 12 -700 -400 100 R 50 50 1 1 B
+X DSR 22 700 300 100 L 50 50 1 1 I
+X GPIO.1 13 -700 -300 100 R 50 50 1 1 B
+X DTR 23 700 400 100 L 50 50 1 1 O
+X GPIO.0 14 -700 -200 100 R 50 50 1 1 B
+X DCD 24 700 500 100 L 50 50 1 1 I
+X ~SUSPEND 15 700 -700 100 L 50 50 1 1 O
+X PAD 25 100 -1000 100 U 50 50 1 1 W
+X VPP 16 -700 -700 100 R 50 50 1 1 P
+X SUSPEND 17 700 -600 100 L 50 50 1 1 O
+X CTS 18 700 -300 100 L 50 50 1 1 I
+X RTS 19 700 -200 100 L 50 50 1 1 O
+ENDDRAW
+ENDDEF
+#
 # CP2112
 #
 DEF CP2112 U 0 40 Y Y 1 F N