'**************************************************************************
'********************** SUBS AND FUNCTIONS ********************************
'**************************************************************************

Sub Mcp2515_bitmodify(byval Reg_addr As Byte , Byval Reg_mask As Byte , Byval Reg_val As Byte)
'Write to certain bits in a MCP2515 register via SPI
'This command ensures that certain bits in a complete register can be changed without affecting the other bits.
'Unlike the "Write" command, this does not change the entire contents of the register. Only the masked bits.

   Local Cmd As Byte

   Reset Mcp2515_cs
   Cmd = Cmd_bit_modify
   Spiout Cmd , 1
   Spiout Reg_addr , 1
   Spiout Reg_mask , 1
   Spiout Reg_val , 1
   Set Mcp2515_cs
End Sub
'**************************************************************************

Function Mcp2515_read(byval Reg_addr As Byte ) As Byte
'Read from a MCP2515 register via SPI
   Local Cmd As Byte
   Reset Mcp2515_cs
   Cmd = Cmd_read
   Spiout Cmd , 1
   Spiout Reg_addr , 1
   Spiin Mcp2515_read , 1
   Set Mcp2515_cs
End Function
'**************************************************************************

Sub Mcp2515_write(byval Reg_addr As Byte , Byval Reg_val As Byte)
'Write to a MCP2515 register via SPI
'Some registers can only be written in CONFIGURATION MODE
'These are:
'  • CNF1, CNF2, CNF3 registers
'  • Txrtsctrl Register
'  • Filter Registers
'  • Mask Registers

   Local Cmd As Byte

   Reset Mcp2515_cs
   Cmd = Cmd_write
   Spiout Cmd , 1
   Spiout Reg_addr , 1
   Spiout Reg_val , 1
   Set Mcp2515_cs
End Sub
'**************************************************************************

Sub Mcp2515_write_array(byval Startaddr As Byte , Data() As Byte , Byval N As Byte)
'Write to N consecutive register addresses
   Local I As Byte

   Reset Mcp2515_cs
   I = Cmd_write
   Spiout I , 1
   Spiout Startaddr , 1
   Spiout Data(i) , N
   Set Mcp2515_cs
End Sub
'**************************************************************************