The Snickerdoodle Book/PlatformController
Contents
Platform Controller
Introduction
Snickerdoodle's platform controller is a STM32F0 series 32-bit ARM®Cortex-A0® microcontroller connected to and in control of various signals. See "Chapter 9" for a bit of an introduction.
15. Peripherals
ADC
Several 12-bit analog to digital converters (ADC) on the platform controller are used to monitor the on-board systems. The power supply levels are monitored using the ADCs.
TODO: insert Table 15.1: ADC Port Connection
I2C
SPI
LEDs
The platform controller is connected to 5 LEDs that are used to indicate various states and events of the board. These LEDs are connected to peripherals that are configured as PWM timers for brightness control on the LEDs through the PWM duty cycle.
| PA8 | D11 | TIM1 CH1 | Red (fault) |
| PC6 | E12 | TIM3 CH1 | Green (USB/Power) |
| PC7 | E11 | TIM3 CH2 | Blue (Bluetooth) |
| PC8 | E10 | TIM3 CH3 | White (Application) |
| PC9 | D12 | TIM3 CH4 | Orange (Wireless Link) |
USART
USART1
USART1 is connected to the Zynq processing subsystem on UART0 and is normally used to bridge the Zynq console output to the USB device peripheral. Normally the USB device is configured as a communications device class (CDC) interface.
| Mode | Asynchronous |
|---|---|
| Hardware Flow Control (RS-232) | Disabled |
| Baud Rate | 115200 |
| Word Length | 8 bits |
| Parity | None |
| Stop Bits | 1 |
| Data Direction | Receive and Transmit |
| Over Sampling | 16 Samples |
| Single Sample | Disable |
USART2
USART2 is connected to the Bluetooth HCI interface of the Wilink 8 module.
TODO: insert Table 15.4: Platform Controller USART2
USB Device
The USB device peripheral is normally configured as a communications device class (CDC) interface to provide access to the Zynq console by bridging to USART1 which is connected to UART0 on the Zynq.
During certain boot modes, the USB device is configured for device firmware upgrade (DFU) and can be used to program the platform controller by writing directly to the embedded flash memory.
Basic Parameters
TODO: insert Table 15.5: USB Parameters
GPIO
| STM32 Port Pin | Zynq Pin | I/O | Description |
|---|---|---|---|
| PA9 | D10 | Output | ANT_SELECT_1 |
| PA10 | C12 | Output | ANT_SELECT_2 |
| PC1 | J2 | Output | ZYNQ_JTAG_NRST |
| PD1 | B9 | Output | ZYNQ_POWER_EN |
| PD2 | C8 | Output | WDI |
| PD7 | A5 | Output | WL_32KHZ_CLK_EN |
| PD8 | K9 | Output | ZYNQ_CLK_EN |
| PE2 | B2 | Output | MIO4_BOOT_SELECT |
| PE3 | A1 | Output | MIO5_BOOT_SELECT |
| PE4 | B1 | Input | SELECT_BUTTON |
| PE5 | C2 | Input | RESET_BUTTON |
| PE7 | M7 | Input | ZYNQ_POWER_GOOD |
| PF10 | G2 | Output | WL18xx_BT_EN |
| PD15 | H10 | Output | SMB_NRESET |
EXTI
| STM32 Port Pin | Zynq Pin | I/O | Description |
|---|---|---|---|
| PD10 | J12 | EXTI10 | JA1_P2 |
| PD11 | J11 | EXTI11 | JA2_P2 |
| PD12 | J10 | EXTI12 | JB1_P2 |
| PD13 | H12 | EXTI13 | JB2_P2 |
| PD14 | H11 | EXTI14 | JC1_P2 |
16. Firmware
The platform controller firmware provides the logic for handling the tasks of the...
Development Environment
The integrated development environment used to target the platform controller is the ARM® Keil microcontroller development kit (MDK). The MDK can be downloaded from http://www2.keil.com/stmicroelectronics-stm32/ mdk. After registering and activating the MDK, custom platform controller firmware can be developed and compiled
17. Device Firmware Upgrade (DFU)
For full customization of the Snickerdoodle system the firmware on the platform controller can be modified and upgraded.
For more details see Firmware section of the krtkl download page.
Booting into DFU
The device firmware upgrade interface can be accessed by pressing and holding down both the SELECT and RESET buttons when powering the board. After holding both buttons for 4 seconds, the device will boot into DFU mode and allow access to program the platform controller with upgrade or even custom firmware. See the DFU wiki page for more info.
Bootloader Pin Activation Pattern
The device system memory bootloader (which includes USBDFU firmware) can be entered when powering up the board by pulling the BOOT0 pin high (+1.8V). This pin is normally pulled to ground through a 100k resistor (R56) but can be connected to +1.8V by carefully shorting the pads for the normally unloaded R55 resistor shown in Figure 17.1 .
WarningBox: WARNING Extreme care should be taken when attempting to connect
the pads on R55. Irreparable damage to the board may occur if
an error is made while shorting the pads. DO NOT use this method
for normal firmware upgrades unless and should only be used if the
firmware DFU mechanism has been disabled.
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Generate Loadable Images
HEX File Build Output
To produce a loadable DFU image, a .hex file is used and must be produced by the firmware build process. To enable .hex file production in the Keil ¹Vision development environment, navigate to Project » Options for Target under the Output tab and check the box marked Create HEX File as shown in Figure 17.2 .
The generated .hex file can be used to create a firmware upgrade image.
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Generate DFU Image
The DFU FileManager (DFUFM) allows users to generate DFU images from firmware build outputs (i. e., S19, HEX or BIN files) and can also be used to extract firmware build outputs from DFU images. For a typical DFU, the DFUFM will be used to produce DFU images by selecting I want to GENERATE a DFU file... after opening the DFUFM. With a .hex file produced from a firmware build, a usable DFU image can be produced. From the DFU File Manager, select S19 or Hex... from the Injection section of the interface and navigate to the .hex file you wish to use for the firmware upgrade and select Generate...
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Perform Firmware Upgrade
As directed in the Snickerdoodle Firmware User Guide in the Firmware section of the krtkl download page, download and install the DfuSeDemo package. The installation directory is typically similar to "C:\Program Files (x86)\STMicroelectronics\Software\DfuSe v3.0.6". That directory tree will contain executables and source code. The bin/doc/UM0412.pdf file will also contain some dated documentation that can still be useful.
The DfuSe interface will detect any microcontrollers that are connected to the host USB in DFU mode as shown in Figure 17.5.
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You will see two "Choose..." buttons in the window. Select the one in the "Upgrade or Verify Action" section of the window. Then select the image file you will be using. The most recent recommended one can be found on the "Firmware" section of the krtkl.com download page. After doing so the window will look similar to Figure 17.6. If instead, the window freezes when you try to select a .dfu file, reboot the machine and start this DfuSeDemo again.
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Select the "Verify after download" and the "Upgrade" button to transfer the image on to the microcontroller as shown in Figure 17.7.
This usually completes in as little as 5 seconds, but we have seen instances where (particular on Lenovo laptops without a USB hub) this can take up to four hours. If you find yourself in a situation where this is running a long time, do not unplug the Snickerdoodle. Instead adjust your Windows10 Power Options so that the computer does not go to sleep before the process is complete. If your computer goes to sleep before the process completes, it can brick your Snickerdoodle.
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When this completes, the window should indicate the process was successful as shown in figure 17.8.
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18. USB Interface (Virtual COM Port)
The USB interface is most commonly specified as a communications class device and used to bridge the UART (RS-232) connection between the platform controller and the application processor.
For more details see Chapter 18 here.
