DeviceFS_CallDevice

Undocumented registers must be used as described inside the part of the RISC OS PRMs which describes DeviceFS_CallDevice. Regard all undocumented registers in range R0-R9 as reserved.

Operation Register Value Meaning
Reset R0 1<<31 + 0 Resets the FTDI chip to defaults but not the device
Flowcontrol Characters R0 1<<31 + 1 Sets and read XON/XOFF flowcontrol characters
R3 New XON character at entry. Old XON character at exit.
R4 New XOFF character at entry. Old XOFF character at exit.
Read Modem Status R0 1<<31 + 2 Read modem status
R3 Contains modem status at exit. See FTDI documentation for explanation of the modem status.
Set Event Character R0 1<<31 + 3 Set event character
R3 New event character at entry. See FTDI documentation for explanation of the event character. Usually usage of event characters is disabled. Setting the character enables usage. You canīt disable usage afterwards until a chip reset is performed.
Set Error Character R0 1<<31 + 4 Set error character
R3 New error character at entry. See FTDI documentation for explanation of the error character. Usually usage of error characters is disabled. Setting the character enables usage. You canīt disable usage afterwards until a chip reset is performed.
Latency Timer R0 1<<31 + 5 Read or set latency timer
R3 0 is a forbidden value for the latency timer. Therefore this value is used to read the value of the latency timer into R3 at exit. Every other value writes the latency timer. See FTDI documentation for explanation of the latency timer.
Set Bit Mode R0 1<<31 + 6 Sets FTDI chip Bit mode
R3

New FTDI chip Bit mode. The operation might failed because not every FTDI chip implements every mode and the driver is not supported every mode. In fact in the moment the driver supports only one mode:

  • 0 - IO-mode (Serial device)
Get EEPROM R0 1<<31 + 7 Read content of the EEPROM which is inbuild in some FTDI chips
R3 Pointer to memory to hold the EEPROM content
R4 Bytes to read from EEPROM
R5 Offset into EEPROM to position to read from.
Set EEPROM R0 1<<31 + 8 Sets FTDI chip Bit mode (Allowance must be set inside configuration)
R3 Pointer to memory holding the data to be written to the EEPROM. The driver knows the EEPROM size and so all data will be written in one go.
Erease EEPROM R0 1<<31 + 9 Ereases the content of the EEPROM (Allowance must be set inside configuration)