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Messages - seo

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1
Thank you for your explanation!

2
Thank you for your reply!

3
Hello,

FTDI Application Note 108 "Command Processor for MPSSE and MCU Host Bus Emulation Modes" suggests the following: "NOTE: To ensure that the device driver will not issue IN requests if the buffer is unable to accept data, add a call to FT_SetFlowControl prior to entering MPSSE or MCU Host Bus modes."

FTDI Application Note 135 "FTDI MPSSE Basics" gives the following wording: "FT_SetFlowControl – Configure for RTS/CTS flow control to ensure that the driver will not issue IN requests if the buffer is unable to accept data."
The code suggested by Application Note 135 is as follows:
FT_SetFlowControl(ftHandle, FT_FLOW_RTS_CTS, 0x00, 0x00); //Turn on flow control to synchronize IN requests

Could you please explain the rationale behind it? Why should we configure for RTS/CTS flow control before entering MPSSE mode? As far as I understand in MPSSE mode there are no pins that would act as RTS and CTS (in the sense as RTS/CTS pins are used e.g. in UART mode).

Thank you in advance!

4
Thank you for your reply!

Application Note 135 "FTDI MPSSE Basics" suggests to make the following call before exiting the program:
FT_SetBitMode(ftHandle, 0x0, 0x00); // Reset the port to disable MPSSE

Do I understand correctly that after this call all the pins ADBUS0-ADBUS7 remain configured as inputs even after the process (that made this call) is terminated? And the pins remain configured as inputs until a new process calls D2XX functions (unless the FTDI USB device is unplugged/plugged or powered-off/powered-on, e.g. when the host computer goes to/from sleep mode)?

Table 7.1 "Default External EEPROM Configuration" of FT232H Datasheet states that the parameter "Pull down I/O Pins in USB Suspend" is Disabled. Table 4.1 "FT232H I/O States" of Application Note 184 "FTDI Device Input Output Pin States" gives the value "Function" for pins ADBUS0-ADBUS7 in the column "SUSPEND (Pull Down IO Pins in USB Suspend - Not Set)". This is why I think that the pins ADBUS0-ADBUS7 should preserve their configuration as inputs even when the host computer puts the FTDI USB device into suspend (after some period of inactivity).

5
Hello,

I use the FTDI cable C232HM-DDHSL-0 that has the FTDI chip FT232H. I use D2XX driver for Linux.

In D2XX Programmer's Guide (in its latest version 1.4) the description of the function FT_SetBitmode states:
"ucMask  Required value for bit mode mask. This sets up which bits are inputs and outputs. A bit value of 0 sets the corresponding pin to an input, a bit value of 1 sets the corresponding pin to an output".

I would like to know what pins of FT232H chip are configured in accordance with ucMask when the function FT_SetBitmode is called? I assume that these are pins ADBUS0..ADBUS7, but I cannot find the confirmation of it in FTDI documentation: I have looked for it in the datasheet for FT232H chip, in D2XX Programmer's Guide, and in FTDI Application Notes 108, 129, 135.

Please advise if this information is covered somewhere in FTDI documentation?

Do I understand correctly that after the call FT_SetBitmode(ftHandle, 0x0, 0x0) all the pins ADBUS0..ADBUS7 of FT232H chip (and the corresponding wires of the C232HM cable) will be configured as inputs?

P.S. I would like to know it because I am going to configure all FT232H pins as inputs until my target device (which I am going to debug with JTAG) is initialized and ready for JTAG communication. It would allow to avoid a possible short circuit in the case if some pins of my target device are configured as outputs in the timeframe after the device is powered on and before it is initialized for JTAG communication. After the target device is ready for JTAG communication I am going to switch FT232H chip to MPSSE mode and then configure pins directions for JTAG communication by means of MPSSE commands.

Thank you in advance!

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