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diff --git a/keyboards/hhkb/yang/memo.md b/keyboards/hhkb/yang/memo.md new file mode 100644 index 0000000000..5c710482b3 --- /dev/null +++ b/keyboards/hhkb/yang/memo.md @@ -0,0 +1,135 @@ +## Hardware Information + +The YANG HHKB BLE controller design is similiar to hasu's +controller. Most pins are compatiable. + +**MCU**: ATmega32U4 +**Bluetooth**: MDBT40 (nRF51822-based), with Adafruit Bluefruit LE UART Friend firmware. +**Power**: 3.3V +**CPU Frequency**: 8MHz +**Bootloader**: Lufa MassStorage + +## Pin usage + +| Description | HASU pin usage | YANG mod changed | +|:------------------------------------ | ---------------------- | -------------------------- | +| ~KEY: Lo(0) when key is pressed | PD7 input(with pullup) | | +| Hysteresis: Hi(1) if key was pressed | PB7 output | | +| Row selector bit0 | PB0 output | | +| Row selector bit1 | PB1 output | | +| Row selector bit2 | PB2 output | | +| Col selector bit0 | PB3 output | | +| Col selector bit1 | PB4 output | | +| Col selector bit2 | PB5 output | | +| Key unable | PB6 output | | +| Switch power | PD4 output | PD6 output (PMOS FET) | +| Bluetooth UART Rx | PC4 input | PD2 | +| Bluetooth UART Tx | PC5 output | PD3 | +| Bluetooth power | | PD5 output (low: power on) | +| LED 0 | | PF4 | +| LED 2 | | PF1 | +| LED 4 | | PF0 | +| Unused for PRO2 | PC6 | | +| Unused for PRO2 | PC7 | | +| Inner USB power | | PF7 | + +## How to flash LUFA MassStorage bootloader on Linux + +The FAT filesystem on Linux very often cannot flush the write cache, +leading to broken firmware in the flash. + +We can use `dd` to write to the virtual block storage directly to +bypass the vfs layer. + +``` +dd if=FLASH.bin of=<path of virtual block device> seek=4 +``` + +Skip 4 sectors because the default sector size of the virtual device +and dd is 512 bytes and the emulated flash file starts at 5th sector. + +## How to find the path of the virtual block device + +After the keyboard boots into flash mode, on Linux system you should +be able to find the block device in `dmesg` logs. + +For exmaple if you type + +``` +sudo dmesg +``` + +You should find something like + +``` +[357885.143593] usb 1-1.4: USB disconnect, device number 24 +[357885.627740] usb 1-1.4: new full-speed USB device number 25 using xhci_hcd +[357885.729486] usb 1-1.4: New USB device found, idVendor=03eb, idProduct=1962, bcdDevice= 0.01 +[357885.729492] usb 1-1.4: New USB device strings: Mfr=0, Product=0, SerialNumber=0 +[357885.745620] SCSI subsystem initialized +[357885.746712] usb-storage 1-1.4:1.0: USB Mass Storage device detected +[357885.746818] scsi host0: usb-storage 1-1.4:1.0 +[357885.746919] usbcore: registered new interface driver usb-storage +[357885.747689] usbcore: registered new interface driver uas +[357886.766755] scsi 0:0:0:0: Direct-Access LUFA Bootloader 0.00 PQ: 0 ANSI: 0 +[357886.773216] scsi 0:0:0:0: Attached scsi generic sg0 type 0 +[357886.777474] sd 0:0:0:0: [sdx] 134 512-byte logical blocks: (68.6 kB/67.0 KiB) +[357886.780300] sd 0:0:0:0: [sdx] Write Protect is off +[357886.780302] sd 0:0:0:0: [sdx] Mode Sense: 00 00 00 00 +[357886.783113] sd 0:0:0:0: [sdx] Asking for cache data failed +[357886.783114] sd 0:0:0:0: [sdx] Assuming drive cache: write through +[357886.842676] sdx: +[357886.859528] sd 0:0:0:0: [sdx] Attached SCSI removable disk +``` + +The `sdx` is the block device name and the full path is at `/dev/sdx` +The above flash command will become + +``` +dd if=FLASH.bin of=/dev/sdx seek=4 +``` + +## Adafruit Bluefruit LE UART configuraton + +The default baud rate used by the firmware is 76800 although adafruit +do not recommend using higher baudrates than 9600 because the nRF51 +UART can drop characters. + +Double speed mode to get more accurate async reading because the F_CPU +speed is 8MHz. + +## Power saving mode design + +Power saving is only enabled when USB is detached and using battery +power. Here we define several levels of power saving mode, each saves +more power but takes longer to resume operation. + +1. Level 1: idle mode is activated after a short configurable time + (MATRIX_POWER_SAVE_TIMEOUT_MS) MCU is put into sleep mode and only + scan the matrix per 15ms. PORTB pins are set to input with pull-up + to save power. Sensing PCB is powered down between scans. + +2. Level 2: after idling for longer (MATRIX_POWER_SAVE_TIMEOUT_L2_MS) + we entry this state. Matrix scan is skipped until the time lapses + 900ms. + +2. Level 3: sleep mode is activated after a longer timeout + (MATRIX_POWER_SAVE_TIMEOUT_L3_MS) Bluetooth module is powered down. + +## Battery reading + +VBAT is connected to AIN6 pin on the MDBT40 module and the AREF pin is +the reference voltage. Doing a ADC with AT+HWDAC=6 will return the +difference between VBAT and VREF. + +It seems when fully charged the ADC read is 550. Likely VREF is 3311mV +and the fully charged VBAT is thus 3861mV. + +Enable battery service with AT+BLEBATTEN=1 first then we can update the +battery level by using AT+BLEBATTVAL=%d + +## References + +* https://github.com/joric/qmk/wiki/hhkb_ble +* https://github.com/tomsmalley/custom-topre-guide +* https://github.com/abcminiuser/lufa/blob/master/Bootloaders/MassStorage/Lib/VirtualFAT.h |