SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The ePWM module represents one complete PWM channel composed of two PWM outputs: EPWMxA and EPWMxB. Multiple ePWM modules are instanced within a device as shown in Figure 14-1. Each ePWM instance is identical with one exception. Some instances include a hardware extension that allows more precise control of the PWM outputs. This extension is the high-resolution pulse width modulator (HRPWM) and is described in Section 14.14. See the device data sheet to determine which ePWM instances include this feature. Each ePWM module is indicated by a numerical value starting with 1. For example, ePWM1 is the first instance and ePWM3 is the third instance in the system and ePWMx indicates any instance.
The ePWM modules are chained together by way of a clock synchronization scheme that allows them to operate as a single system when required. Additionally, this synchronization scheme can be extended to the capture peripheral submodules (eCAP). The number of submodules is device-dependent and based on target application needs. Submodules can also operate standalone.
Each ePWM module supports the following features:
Each ePWM module is connected to the input/output signals shown in Figure 14-1. The signals are described in detail in subsequent sections.
The order in which the ePWM modules are connected can differ from what is shown in Figure 14-1. See Section 14.4.3.3 for the synchronization scheme for a particular device. Each ePWM module consists of eight submodules and is connected within a system by way of the signals shown in Figure 14-2.
Figure 14-3 shows more internal details of a single ePWM module. The main signals used by the ePWM module are:
The PWM output signals are made available external to the device.
These input signals alert the ePWM module of fault conditions external to the ePWM module. Each submodule on a device can be configured to either use or ignore any of the trip-zone signals. The TZ1 to TZ3 trip-zone signals can be configured as asynchronous inputs through the GPIO peripheral using the Input X-BAR logic, refer to Figure 14-50. TZ4 is connected to an inverted EQEPx error signal (EQEPxERR), which can be generated from any one of the EQEP submodule (for those devices with an EQEP module). TZ5 is connected to the system clock fail logic, and TZ6 is connected to the EMUSTOP output from the CPU. This allows configuring a trip action when the clock fails or the CPU halts.
The synchronization signals daisy chain the ePWM modules together. Each module can be configured to either use or ignore the synchronization input. The clock synchronization input and output signal are brought out to pins only for ePWM1 (ePWM module #1). The ePWM modules are separated into groups of three for syncing purposes. An external sync signal (EXTSYNCIN1 or EXTSYNCIN2) can be used to issue a sync signal to the first ePWM module in each chain. These same modules can also send the EPWMxSYNCOUT signal to a GPIO. For more information, see Section 14.4.3.3.
Each ePWM module also generates another PWMSYNC signal called EPWMxSYNCPER. EPWMxSYNCPER goes to the GPDAC and CMPSS for synchronization purposes. Functionality is configured using the HRPCTL register, but has no relation with the HRPWM. For more information on how EPWMxSYNCPER is used by the GPDAC and CMPSS, see the respective chapters.
Each ePWM module has two ADC start of conversion signals. Any ePWM module can trigger a start of conversion. Whichever event triggers the start of conversion is configured in the event-trigger submodule of the ePWM.
Output signals from the comparator module can be fed through the Input X-BAR and EPWM X-BAR to one or all of the 12 trip inputs [TRIPIN1 - TRIPIN12] and in conjunction with the trip zone signals can generate digital compare events.
The peripheral bus is 32-bits wide and allows both 16-bit and 32-bit writes to the ePWM register file.