BasicPI

Baudrates like 110, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 38400, 57600, 115200, 230400, 460800, 921600 are rather standard, but what do you use to set 10Mbps?

Testing with a Windows PC I manage to get 2Mbps as shown here, but Windows is not able to open higher frequencies. I am in this case using USART6 on STM32F405 capable of 10Mbps speed, so it’s Windows that is the limitation.

This was a rare bug on the XPortHub! I have not bothered to test the super-cap/battery for the VBAT much, but suddenly realized as I was doing other changes that I had an error message related to this. And correct – measuring the PCB I have a self infected short-cut. CNC machinery making PCB’s require a minimum of 0.14mm distance between lanes to guarantee that lanes are not shorted and this is shorted by accident.

The EDA warns me, so this is me overlooking the error message. I have a package overlap here because I have an alternative connector – this generate error messages I have to overlook and I obviously overlooked one I should not have overlooked. It’s no big deal because this could very well have been connected. The only component I shortcut is a diode that should prevent leakage back to other circuitry. But, it means the battery will power the entire circuit, not just VBAT.

I keep repeating myself – I always need a minimum of 2 PCB layout’s. The more I push to work faster the more of these minor bugs I am guaranteed – but, that is ok – I just plan for it.In this case I want to add a proper battery holder on 1.1 anyway.

FATFS is a middleware component you can add to create a MicroSD API with full file I/O support. It only takes a few clicks with CubeMX and you have an API with the following and more:

• f_mount(): Register/Unregister a work area
• f_open(): Open/Create a file
• f_close(): Close a file
• f_read(): Read a file
• f_write(): Write a file
• f_lseek(): Move read/write pointer, Expand a file size
• f_truncate(): Truncate a file size
• f_sync(): Flush cached data
• f_opendir(): Open a directory
• f_readdir(): Read a directory item
• f_getfree(): Get free clusters
• f_stat(): Check if the object is exist and get status
• f_mkdir(): Create a directory
• f_unlink(): Remove a file or directory
• f_chmod(): Change an attribute
• f_utime(): Change timestamp
• f_rename(): Rename/Move a file or directory
• f_chdir(): Change the current directory
• f_chdrive(): Change the current drive
• f_getcwd(): Retrieve the current directory
• f_getlabel(): Get volume label
• f_setlabel(): Set volume label
• f_forward(): Forward file data to the stream directly
• f_mkfs(): Create a file system on the drive
• f_fdisk(): Devide a physical drive
• f_gets(): Read a string
• f_putc(): Write a character
• f_puts(): Write a string
• f_printf(): Write a formatted string
• f_tell(): Get the current read/write pointer
• f_eof(): Test for end-of-file on a file
• f_size(): Get the size of a file
• f_error(): Test for an error on a file
• disk_initialize(): Initializes the physical  disk drive
• disk_status(): Returns the selected physical drive status
• disk_read(): Reads sector(s) from the disk
• disk_write(): Writes sector(s) to the disk
• disk_ioctl(): Controls device-specified features
• get_fattime(): Returns the current time

I finally managed to sort out the CubeMX/SW4STM32 error so I can move on a bit. The XPortHub (pictured above) is coming together very well. Sadly I have to upgrade this due to the Flash footprint error, so I will make some other adjustments as well.

CubeMX auto-generate all drivers with pin-setting, FreeRTOS, USB driver and even the FATFS system allowing the Micro SD Card to be used as a disk.

The pin-out above shows how dense this design is getting with only 5 spare pins. Using the USB as a serial link with a little console app this basically have more content than my first IBM PC back in 1983. It bring back some nostalgic reflections to my early days fiddling with DOS and C compilers.

What I will do next is actually to create a terminal application and a CLI with a Utility package that in many ways with mimic the old DOS/Console days.

I would like to simplify all Java applications, so I suggest I create my own Java 3 VM. It will only need one instruction:

CRASH

I had a project for XPortHub in CubeMX that worked well, upgraded CubeMX and shit hit the fan. Obviously the new CubeMX generate or don’t generate some script that SW4STM32 don’t like. I like CubeMX, but I am not impressed with ST Microelectronics complete lack of SW quality! I will get around this, but it is a major time-waster!

Soldering 0.5 pitch components is a challenge to get right. My latest problem have been cold soldering. Meaning that pins look ok, but as I test them I have no connection. Not sure if this is lack of temperature, lack of solder tin or what, but I will have to find a more reliable way because it has caused a lot of issues lately.

The illustration above shows the problem. Pins look as if they are soldered, but in fact they are not. I suspect a combination of to little paste and to low temperatures, but lets see.

Having MCU’s you don’t trust don’t help, but just for the record the one I tested did work!

It is rare that I receive chips from China as unprofessional as these, but it does happen. I have no idea if these works at all yet, but we will see. If not the seller will loose out. I actually mounted a XPortHub, so we will see – but, this is why I want to build the test-bench with sockets.

   This is the XPortHub mounted on top of a Rapsberry PI A+. The only lacking components are the SuperCap + the Serial Flash. I made the package for W25Q16 myself so I have no-one else to blame, but I have used a standard SO8 rather than the wider SO-8 footprint that I needed – bummer. Well, rev 1.1 coming up I guess.All in all I am quite happy with this Board.