-LOCATE COMP "rpi_pin_11" SITE "D5";
-LOCATE COMP "rpi_pin_12" SITE "G5";
-LOCATE COMP "rpi_pin_22" SITE "E4";
-LOCATE COMP "rpi_pin_29" SITE "E3";
-LOCATE COMP "rpi_pin_31" SITE "E5";
-LOCATE COMP "rpi_pin_32" SITE "D1";
-LOCATE COMP "rpi_pin_33" SITE "F5";
-LOCATE COMP "rpi_pin_35" SITE "A2";
-LOCATE COMP "rpi_pin_36" SITE "C1";
-LOCATE COMP "rpi_pin_37" SITE "B1";
-LOCATE COMP "rpi_pin_38" SITE "C2";
-LOCATE COMP "rpi_pin_40" SITE "B2";
-
-LOCATE COMP "rtc_mfp" SITE "E2";
-LOCATE COMP "rtc_scl" SITE "B3";
-LOCATE COMP "rtc_sda" SITE "A3";
-
-LOCATE COMP "spi_cs0" SITE "E1";
-LOCATE COMP "spi_cs1" SITE "D2";
-LOCATE COMP "spi_miso" SITE "D3";
-LOCATE COMP "spi_mosi" SITE "C3";
-LOCATE COMP "spi_sclk" SITE "F4";
-
-LOCATE COMP "tuner_hf" SITE "D8";
+# reaspberry pi header
+# pin 1: 3v3 n/c
+# pin 2: 5v
+LOCATE COMP "rtc_sda" SITE "A3"; # pin 3: gpio2 SDA
+# pin 4: 5v
+LOCATE COMP "rtc_scl" SITE "B3"; # pin 5: gpio3 SCL
+# pin 6: GND
+LOCATE COMP "rtc_mfp" SITE "E2"; # pin 7: gpio4
+LOCATE COMP "uart_rx" SITE "G3"; # pin 8: gpio14 TXD
+# pin 9: GND
+LOCATE COMP "uart_tx" SITE "H3"; # pin 10: gpio15 RXD
+LOCATE COMP "rpi_pin_11" SITE "D5"; # pin 11: gpio17
+LOCATE COMP "rpi_pin_12" SITE "G5"; # pin 12: gpio18
+# pin 13: gpio27 - TMS U5
+# pin 14: GND
+# pin 15: gpio22 - TDI R5
+# pin 16: gpio23 - TCK T5
+# pin 17: 3v3 n/c
+# pin 18: gpio24 - TDO V4
+LOCATE COMP "spi_mosi" SITE "C3"; # pin 19: gpio10 MOSI
+# pin 20: GND
+LOCATE COMP "spi_miso" SITE "D3"; # pin 21: gpio9 MISO
+LOCATE COMP "rpi_pin_22" SITE "E4"; # pin 22: gpio25
+LOCATE COMP "spi_sclk" SITE "F4"; # pin 23: gpio11 CLK
+LOCATE COMP "spi_cs0" SITE "E1"; # pin 24: gpio8 CS0
+# pin 25: GND
+LOCATE COMP "spi_cs1" SITE "D2"; # pin 26: gpio7 CS1
+# pin 27: gpio0 - sda HAT eeprom
+# pin 28: gpio1 - scl HAT eeprom
+LOCATE COMP "rpi_pin_29" SITE "E3"; # pin 29: gpio5
+# pin 30: GND
+LOCATE COMP "rpi_pin_31" SITE "E5"; # pin 31: gpio6
+LOCATE COMP "rpi_pin_32" SITE "D1"; # pin 32: gpio12
+LOCATE COMP "rpi_pin_33" SITE "F5"; # pin 33: gpio13
+# pin 34: GND
+LOCATE COMP "rpi_pin_35" SITE "A2"; # pin 35: gpio19
+LOCATE COMP "rpi_pin_36" SITE "C1"; # pin 36: gpio16
+LOCATE COMP "rpi_pin_37" SITE "B1"; # pin 37: gpio26
+LOCATE COMP "rpi_pin_38" SITE "C2"; # pin 38: gpio20
+# pin 39: GND
+LOCATE COMP "rpi_pin_40" SITE "B2"; # pin 40: gpio21
+
+IOBUF PORT "rtc_sda" IO_TYPE=LVCMOS33;
+IOBUF PORT "rtc_scl" IO_TYPE=LVCMOS33;
+IOBUF PORT "rtc_mfp" IO_TYPE=LVCMOS33;
+IOBUF PORT "uart_rx" IO_TYPE=LVCMOS33;
+IOBUF PORT "uart_tx" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_11" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_12" IO_TYPE=LVCMOS33;
+IOBUF PORT "spi_mosi" IO_TYPE=LVCMOS33;
+IOBUF PORT "spi_miso" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_22" IO_TYPE=LVCMOS33;
+IOBUF PORT "spi_sclk" IO_TYPE=LVCMOS33;
+IOBUF PORT "spi_cs0" IO_TYPE=LVCMOS33;
+IOBUF PORT "spi_cs1" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_29" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_31" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_32" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_33" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_35" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_36" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_37" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_38" IO_TYPE=LVCMOS33;
+IOBUF PORT "rpi_pin_40" IO_TYPE=LVCMOS33;
+
+
+LOCATE COMP "tuner_hf" SITE "D8"; # ADG918 switch lf/hf