STM32L476VGT6 problem with sending commands in QPI mode
Hi,
I’m using STM32L476VGT6 device with external flash memory in QPI mode. Everything works fine until I try to send a command byte with no address and no data. For example, when I try to send the command 0xF5 (exit QPI mode), on the logic analyzer I can see that line IO1 is not controlled by the MCU and stays low. But with the same configuration, when I add address byte everything works well again. It looks like with just command byte sent, line IO1 stays in MISO mode instead of QPI mode.
Pinout of the logic analyzer:
CS – 6
CLK – 4
IO0 – 7
IO1 – 5
IO2 – 3
IO3 – 2
Sending command 0xF5 with no address and no data.
CCR register value is 0x3F5:
Instruction – 0xF5
IMOD – Instruction on four lines
Sending command 0xF5 with one address byte and no data.
CCR register value is 0xFF5:
Instruction – 0xF5
IMOD – Instruction on four lines
AMODE – Address on four lines
On the first capture the IO1 line (pin 5) stays low during the command phase, but on the second capture the IO1 line goes high as it should. What could be the cause of this problem? I would appreciate all help.