Answer

To use the Comparator0 as a wake-up source from the low power modes of the C8051F96x devices, the following steps are required:

1) Firmware must configure the desired wake-up sources (Comparator0 in this case) and clear the wakeup flags in the PMU0CF and PMU0FL registers.  

2) Enter the desired low power mode by writing a '1' to the SLEEP or SUSPEND bits in the PMU0CF register.

Attached to this article is an example project for the C8051F960-TB that demonstrates using the Comparator0 as a wakeup source for the device (F96x_SleepMode_ComparatorWake.zip).  This code can be modified to put the device into SLEEP or SUSPEND mode.

To import this project into Simplicity Studio, follow these steps:

1) Do not unzip the file.

2) In the Simplicity Studio IDE, click [File] > [Import...]

3) Select [Existing Projects into Workspace] > [Next...]

4) Click [Select archive file] > [Browse...] and navigate to the location of the .zip file.  

5) Select the .zip file and click [Open]

6) The project "F96x_SleepMode_ComparatorWake" and click [Finish]

As for routing the Comparator0 output to a port pin, it is possible to route either the latched/synchronous comparator output value (CP0) or the asynchronous output value (CP0A) to a port pin via the crossbar on the C8051F960. The code necessary to do this is posted below, however neither signal will be available on the port pin when the device is in SLEEP mode, as the output value of the port pins are latched in SLEEP mode. You can, however, produce the CP0A signal on a port pin while the device is in SUSPEND mode, as the port pins values are not latched. Level changes on the comparator output that result in the wake event for the device do not appear on the pin when the device is in SLEEP mode, but after the device wakes, it is possible to see the comparator output on the pin. Conversely, when the device is in SUSPEND, it is possible to see the CP0A (asynchronous only) signal on that pin before and after the device has woken from SUSPEND.  It is not possible to output the synchronous comparator output on a pin in either SLEEP or SUSPEND mode, as the clock that latches the synchronous output value to the output buffer is not active in these low power modes.

To enable the Comparator0 output on a port pin, the following steps are required:

1) In the XBR0 register, enable comparator synchronous/CP0 output (XBR0 |= 0x10 or asynchronous/CP0A output (XBR0 |= 0x20.

2) Ensure that port pin you wish to use is configured as a digital output.

3) Skip any pins necessary to assign CPT0 output to your desired pin. For instance, if you wish to use P0.4, and assuming that you are not using any higher priority digital peripherals on the crossbar (UART0, SPI1, SPI0, or SMBus), then you would need to skip pins P0.0 - P0.3 (P0SKIP |= 0x0F.

Thus, to enable the asynchronous CP0A output to pin P0.4, the following code should be added to the COMPARATOR0_Init() routine:

XBR0 |= 0x20; // enable CPT0A asynchronous output to pin 
P0MDOUT |= 0x10; // set P0.4 to push-pull 
P0SKIP |= 0x0F; // skip P.0.0-P0.3 on crossbar - this should put CP0A on P0.4 

Answer

The CS0 module present on the C8051F97x, C8051F99x, and EFM8SB1 devices has its own dedicated oscillator which is active whenever the module is enabled.  Thus, the choice of oscillator source for SYSCLK  will not affect the conversion times specified in the datasheet (which are for the default configuration).

Other factors that might affect the conversion time (or the time between conversion complete interrupts) are the accumulator setting (CS0ACU in CS0CF) and the conversion rate (CS0CR in CS0MD2 - though this is covered in the default electrical specifications).

Answer

It is possible to include the necessary file paths in the build commands for projects in which all header files are located in directories that are relative to the directory containing the project ".wsp" file (and where this relative structure will be maintained no matter where a user pulls down the repository).  This will be the case when the ".wsp" file is located in the project root directory and all necessary header files are located in this root directory or sub-directories of the root.

In the example case I am using to illustrate this technique, the project ".wsp" file is located in a particular directory, and the needed .h files are located in a sub-directory that is two levels down from the ".wsp" file. In the IDE, if you click Project -> Tool Chain Integration -> Compiler Tab, you must add the command line directive:

INCDIR(<relative path from .wsp file to .h include directory>)

In this case, all the header files needed to be included are in the ".\extra_layer_to_test_relative paths\inc" directory.  In the case that there were also header files in the root directory (".\") and in the ".\extra_layer_to_test_relative paths" directory, the needed compiler directive would be:

INCDIR(.\; .\extra_layer_to_test_relative paths; .\extra_layer_to_test_relative paths\inc)

On occasion, users have reported an unusual situation in which some combinations of header files that themselves include other header files in a different part of the directory structure fail to compile, with the compiler warning that the file in the lower level of the directory path could not be opened.  For instance, in this example say that a header file located in the ".\extra_layer_to_test_relative paths\inc" directory includes a file located in the ".\" directory.  If the subsequent file could not be found by the compiler, it may be necessary to add the relative path "..\.." to the path list:

INCDIR(.\; .\extra_layer_to_test_relative paths; .\extra_layer_to_test_relative paths\inc; ..\..)

Answer

When using the Keil compiler, one of the build outputs is the memory usage of the program. Check the Console window of the Simplicity Studio IDE, and the 4th to last line of the build will show the "Program Size." It will show the Data memory usage, xdata usage, const size, and code size. Here's a sample Program Size line that shows data usage of 10.1 bytes and code size of 340 bytes:

Program Size: data=10.1 xdata=0 const=0 code=340

Note that the size will not be output if the build is not successful.

答案

该保留变量确保程序中不使用XDATA RAM外部数据存储器的第一个字节，以应对EFM8SB1器件存在的问题。

参照EFM8SB1 参考手册，第2.3章节：

"Note: On device reset or upon waking up from Sleep mode, address 0x0000 of external memory (XRAM) may be overwritten by an indeterminate value. The indeterminate value is 0x00 in most situations. A dummy variable should be placed at address 0x0000 in external memory to ensure that the application firmware does not store any data that needs to be retained through reset or Sleep at this memory location."

Answer

The only difference is the temperature grade. The I grade devices are production tested for operation at an extended temperature range compared to the G grade devices.

Temperature range is -40 to +85 °C for EFM8BB1/2/3 -G grade devices and -40 to +125 °C for -I grade devices.