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Discussion - Drivers / FT_SetFlowControl: configuring flow control before entering MPSSE mode
« on: March 29, 2021, 09:35:08 AM »
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!
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!