diff --git a/src/energenie/drv/hrf69.c b/src/energenie/drv/hrf69.c
index 652ff47..b2c297b 100644
--- a/src/energenie/drv/hrf69.c
+++ b/src/energenie/drv/hrf69.c
@@ -8,6 +8,7 @@
 //def warning(msg):
 //    print("warning:" + str(msg))
 
+
 //def trace(msg):
 //    print(str(msg))
 
@@ -19,33 +20,163 @@
 //    return line
 
 
+
+void HRF_writereg(uint8_t addr, uint8_t data)
+{
 //def HRF_writereg(addr, data):
+//    """Write an 8 bit value to a register"""
+//    buf = [addr | MASK_WRITE_DATA, data]
+//    spi.select()
+//    spi.frame(buf)
+//    spi.deselect()
+}
 
+
+uint8_t HRF_readreg(uint8_t addr)
+{
 //def HRF_readreg(addr):
+//    """Read an 8 bit value from a register"""
+//    buf = [addr, 0x00]
+//    spi.select()
+//    res = spi.frame(buf)
+//    spi.deselect()
+//    return res[1] # all registers are 8 bit
+}
 
+
+void HRF_writefifo_burst(uint8_t* buf uint8_t len)
+{
 //def HRF_writefifo_burst(buf):
+//    """Write all bytes in buf to the payload FIFO, in a single burst"""
+//    # Don't modify buf, in case caller reuses it
+//    txbuf = [ADDR_FIFO | MASK_WRITE_DATA]
+//    for b in buf:
+//      txbuf.append(b)
+//    spi.select()
+//    spi.frame(txbuf)
+//    spi.deselect()
+}
 
+
+//TODO where is the buffer memory defined?
+//perhaps pass in buffer memory and maxlen
+//how do we know the actual length of buffer written to?
+//pass in ptr to len variable
+uint8_t* HRF_readfifo_burst(void)
+{
 //def HRF_readfifo_burst():
+//    """Read bytes from the payload FIFO using burst read"""
+//    #first byte read is the length in remaining bytes
+//    buf = []
+//    spi.select()
+//    spi.frame([ADDR_FIFO])
+//    count = 1 # read at least the length byte
+//    while count > 0:
+//        rx = spi.frame([ADDR_FIFO])
+//        data = rx[0]
+//        if len(buf) == 0:
+//            count = data
+//        else:
+//            count -= 1
+//        buf.append(data)
+//    spi.deselect()
+//    return buf
+}
 
+
+HRF_RESULT HRF_checkreg(uint8_t addr, uint8_t mask, uint8_t value)
+{
 //def HRF_checkreg(addr, mask, value):
+//    """Check to see if a register matches a specific value or not"""
+//    regval = HRF_readreg(addr)
+//    #print("addr %d mask %d wanted %d actual %d" % (addr,mask,value,regval))
+//    return (regval & mask) == value
+}
 
+
+void HRF_pollreg(uint8_t addr, uint8_t mask, uint8_t value)
+{
 //def HRF_pollreg(addr, mask, value):
+//    """Poll a register until it meet some criteria"""
+//    while not HRF_checkreg(addr, mask, value):
+//        pass
+}
 
+
+void HRF_wait_ready(void)
+{
 //def HRF_wait_ready():
+//    """Wait for HRF to be ready after last command"""
+//    HRF_pollreg(ADDR_IRQFLAGS1, MASK_MODEREADY, MASK_MODEREADY)
+}
 
+
+void HRF_wait_txready(void)
+{
 //def HRF_wait_txready():
+//    """Wait for HRF to be ready and ready for tx, after last command"""
+//    HRF_pollreg(ADDR_IRQFLAGS1, MASK_MODEREADY|MASK_TXREADY, MASK_MODEREADY|MASK_TXREADY)
+}
 
+
+void HRF_change_mode(uint8_t mode)
+{
 //def HRF_change_mode(mode):
+//    HRF_writereg(ADDR_OPMODE, mode)
+}
 
+
+void HRF_clear_fifo(void)
+{
 //def HRF_clear_fifo():
+//    """Clear any data in the HRF payload FIFO by reading until empty"""
+//    while (HRF_readreg(ADDR_IRQFLAGS2) & MASK_FIFONOTEMPTY) == MASK_FIFONOTEMPTY:
+//        HRF_readreg(ADDR_FIFO)
+}
 
+
+HRF_RESULT HRF_check_payload(void)
+{
 //def HRF_check_payload():
+//    """Check if there is a payload in the FIFO waiting to be processed"""
+//    irqflags1 = HRF_readreg(ADDR_IRQFLAGS1)
+//    irqflags2 = HRF_readreg(ADDR_IRQFLAGS2)
+//    return (irqflags2 & MASK_PAYLOADRDY) == MASK_PAYLOADRDY
+}
 
+
+//TODO unnecessary level of runtime indirection?
+//TODO where is the buffer memory defined?
+//perhaps pass in buffer memory and maxlen
+//how do we know the actual length of buffer written to?
+//pass in ptr to len variable
+uint8_t* HRF_receive_payload(void)
+{
 //def HRF_receive_payload():
+//    """Receive the whole payload"""
+//    return HRF_readfifo_burst()
+}
 
+
+void HRF_send_payload(uint8_t* payload, uint8_t len)
+{
 //def HRF_send_payload(payload):
+//    HRF_writefifo_burst(payload)
+//    HRF_pollreg(ADDR_IRQFLAGS2, MASK_PACKETSENT, MASK_PACKETSENT)
+//    reg = HRF_readreg(ADDR_IRQFLAGS2)
+//    if ((reg & MASK_FIFONOTEMPTY) != 0) or ((reg & MASK_FIFOOVERRUN) != 0):
+//        warning("Failed to send payload to HRF")
+}
 
+
+void HRF_config(HRF_CONFIG_REC* config, uint8_t len)
+{
 //def HRF_config(config):
+//    """Load a table of configuration values into HRF registers"""
+//    for cmd in config:
+//        HRF_writereg(cmd[0], cmd[1])
+//        HRF_wait_ready()
+}
 
 
 //# END
diff --git a/src/energenie/drv/hrf69.h b/src/energenie/drv/hrf69.h
index f17242a..0dd9a63 100644
--- a/src/energenie/drv/hrf69.h
+++ b/src/energenie/drv/hrf69.h
@@ -10,6 +10,8 @@
 #ifndef _HRF69_H
 #define _HRF69_H
 
+#include "system.h"
+
 typedef uint8_t HRF_RESULT;
 
 typedef struct