Hi all.
I have a suspicion that needs confirmation Image may be NSFW.
Clik here to view.
As the subject says, I'm trying two SC16IS752 chips on SPI0 and SPI1 to make four UARTs.
Since I had no luck with some Waveshare HATs I acquire some OEM / NoName board that have required configuration.
I've added SPI related lines in config.txtand rebooted
After reboot dmesg shows SPI devices with serial portsthere are interruptsand also two gpiochips 1 and 2 showed up in /devso four serial ports became availableand pinctrl and gpioinfo also seems that have all that SPI communication needs, MISO MOSI SCLK and everythingWith all of the above, I assumed that I can now test serial ports so I started some python program to initialize those ports and periodically send something on each one of them. Python did not return any error and started looping. But there is no Rx Tx led indications on the SC16IS752 outputs on any port.
I checked interrupts again and periodically they was increasing while Python runs.Now I'm pretty sure that on the RPi side, both HW and SW related, everything is OK and that I must pull out my oscilloscope and logic analyzer to debug connections and communications between RPi GPIO header and SC16IS752 chips.
Am I right or am I missing something on the RPi side?
Thanks
I have a suspicion that needs confirmation Image may be NSFW.
Clik here to view.
As the subject says, I'm trying two SC16IS752 chips on SPI0 and SPI1 to make four UARTs.
Since I had no luck with some Waveshare HATs I acquire some OEM / NoName board that have required configuration.
I've added SPI related lines in config.txt
Code:
dtparam=spi=ondtoverlay=sc16is752-spi0,int_pin=25dtoverlay=sc16is752-spi1,int_pin=24After reboot dmesg shows SPI devices with serial ports
Code:
$ dmesg | grep spi[ 67.027439] spi0.0: ttySC0 at I/O 0x0 (irq = 160, base_baud = 921600) is a SC16IS752[ 67.043103] spi0.0: ttySC1 at I/O 0x1 (irq = 160, base_baud = 921600) is a SC16IS752[ 67.062561] spi1.0: ttySC2 at I/O 0x0 (irq = 161, base_baud = 921600) is a SC16IS752[ 67.064151] spi1.0: ttySC3 at I/O 0x1 (irq = 161, base_baud = 921600) is a SC16IS752Code:
$ cat /proc/interrupts | grep spi 53: 0 ARMCTRL-level 61 Edge 20215080.spi 78: 0 ARMCTRL-level 86 Edge 20204000.spi160: 0 pinctrl-bcm2835 25 Level spi0.0161: 0 pinctrl-bcm2835 24 Level spi1.0Code:
$ ls -l /dev/gpio*crw-rw----+ 1 root gpio 254, 0 Apr 9 14:23 /dev/gpiochip0crw-rw----+ 1 root gpio 254, 1 Apr 9 14:24 /dev/gpiochip1crw-rw----+ 1 root gpio 254, 2 Apr 9 14:24 /dev/gpiochip2lrwxrwxrwx 1 root root 9 Apr 9 14:23 /dev/gpiochip4 -> gpiochip0Code:
$ ls -l /dev/ttyS*crw-rw---- 1 root dialout 4, 64 Apr 9 14:23 /dev/ttyS0crw-rw---- 1 root dialout 239, 0 Apr 9 14:24 /dev/ttySC0crw-rw---- 1 root dialout 239, 1 Apr 9 14:24 /dev/ttySC1crw-rw---- 1 root dialout 239, 2 Apr 9 14:24 /dev/ttySC2crw-rw---- 1 root dialout 239, 3 Apr 9 14:24 /dev/ttySC3Code:
$ pinctrl | grep SPI 9: a0 -- | lo // GPIO9 = SPI0_MISO10: a0 -- | lo // GPIO10 = SPI0_MOSI11: a0 -- | lo // GPIO11 = SPI0_SCLK19: a4 -- | lo // GPIO19 = SPI1_MISO20: a4 -- | lo // GPIO20 = SPI1_MOSI21: a4 -- | lo // GPIO21 = SPI1_SCLKCode:
$ gpioinfo | grep spiline 7: "GPIO7" "spi0 CS1" output active-low [used]line 8: "GPIO8" "spi0 CS0" output active-low [used]line 18: "GPIO18" "spi1 CS0" output active-low [used]line 7: "GPIO7" "spi0 CS1" output active-low [used]line 8: "GPIO8" "spi0 CS0" output active-low [used]line 18: "GPIO18" "spi1 CS0" output active-low [used]I checked interrupts again and periodically they was increasing while Python runs.
Code:
$ cat /proc/interrupts | grep spi 53: 286 ARMCTRL-level 61 Edge 20215080.spi 78: 95 ARMCTRL-level 86 Edge 20204000.spi160: 0 pinctrl-bcm2835 25 Level spi0.0161: 8 pinctrl-bcm2835 24 Level spi1.053: 322 ARMCTRL-level 61 Edge 20215080.spi 78: 107 ARMCTRL-level 86 Edge 20204000.spi160: 0 pinctrl-bcm2835 25 Level spi0.0161: 8 pinctrl-bcm2835 24 Level spi1.053: 839 ARMCTRL-level 61 Edge 20215080.spi 78: 276 ARMCTRL-level 86 Edge 20204000.spi160: 0 pinctrl-bcm2835 25 Level spi0.0161: 20 pinctrl-bcm2835 24 Level spi1.0Am I right or am I missing something on the RPi side?
Thanks
Statistics: Posted by freedom74 — Thu Apr 10, 2025 12:49 pm