MSP430F67791A: Purpose for EEPROM in TIDM-THDREADING design

Hello Dan,

I created a new thread, since this question is different than your initial question in the thread below. Please keep this in mind for future questions.

To answer your question, the EEPROM is used to store multi-rate schedules related to different time slots, holidays, cutoff dates, daily peaks, etc. Multi-rate features vary considerably. This software provides sophisticated multi-rate features, for single and 3-phase meters. It does this with very modest Flash or RAM usage. The software can store all schedules, and recorded usage, in an external EEPROM. However, the schedules can be stored in a section of the MCU's Flash.

For more details about the EEPROM, I would encourage you to search for "EEPROM" in the source code and header files. It appears that the external EEPROM support is disabled by default in the 'emeter.h' file. Other helpful files include 'emeter-3ph-neutral-6779.h', 'iiceeprom.c', 'emeter-structs.h', 'emeter-toolkit-custom.h', and 'emeter-multirate.h'.

/* Many data logging requirements can be met by using only the MSP430's
   info memory. If an external serial EEPROM is needed for more
   complex requirements, this switch will enable an interface to
   I2C type serial EEPROMs. Basic routines to driver these EEPROMs are
   included in the toolkit. Routines to actually store and retrieve
   information are left to the meter designer. */
#undef EXTERNAL_EEPROM_SUPPORT

Regards,

James

MSP Customer Applications

Hello,

Thanks for the additional details, and I understand your concern. Unfortunately, we don't have source code that matches your application exactly. However, it's a good start and looking at the 'metrology-template.h' file, you can change the number of phases to two (#define NUM_PHASES  2), the number of voltage channels to two (#define VOLTAGE_CHANNELS  2), and then the number of current channels to four (#define CURRENT_CHANNELS  4). From my experience with the code, there's logic that should automatically make changes to structures, etc. for the different phase and channel configuration. Next, you'd want to define which channels are doing what (e.g. Channel 0 is Line 1, Channel 1 is Line 2, Channel 2 is Current 1, etc.). The channel allocation is done in the 'metrology-template.h' file (see code below).

/*! ADC channel allocation */
#define PHASE_1_VOLTAGE_ADC_CHANNEL                 0
#define PHASE_1_CURRENT_ADC_CHANNEL                 4
#define PHASE_2_VOLTAGE_ADC_CHANNEL                 1
#define PHASE_2_CURRENT_ADC_CHANNEL                 5
#define PHASE_3_VOLTAGE_ADC_CHANNEL                 2
#define PHASE_3_CURRENT_ADC_CHANNEL                 6
#define NEUTRAL_CURRENT_ADC_CHANNEL                 3

I'm confident that the MSP430F6779(A) can meet your requirements since it supports 7 channels. Again, I would still recommend purchasing the EVM430-F6779, getting familiar with the code, and then modifying the channel configurations from three to two.

If you aren't able to purchase an EVM yet, perhaps getting the target development board for the MSP430F6779(A) and inputting differential AC signals (below the Full Scale Range obviously) using signal generators will help. Here, you could create phase shifts between the channels to see how the phase angles are measured.

Regards,

James

MSP Customer Applications

Hello Dan,

Thanks for your patience.

I’m happy to inform you that the official software release for the new Energy Measurement Design Center and Software Library is available on TI.com. It supports CCS and includes documentation and Design Center examples for the supported EVMs. Please download and install the release from the following link:

Let me know if you have any questions.

Regards,

James

MSP Customer Applications

Hello Dan,

Sounds like you're making great progress! I believe that the EVM430-F6779 does feature the 100-pin version of the F6779(A), so as long as you make all the same connections, the same firmware base should work. I'm glad that you're using the A-version and not the F6779, since it has several improvements.

Be mindful of the AUX1, AUX2, and AUX3 connections. I would recommend referring to the Battery Management and Auxiliary Power Supply Options for E-Meters TI Design (TIDM-AUX-MODULE) and its user's guide for some helpful examples for making those connections.

Has the new EMDC tool been helpful on the software development front? If you have any feedback, let me know!

EDIT: The EVM430-F6779 features the 128-pin version, not the 100-pin version.

Regards,

James

MSP Customer Applications

Hello Dan,

First, let me point out that I was wrong in my earlier post. The EVM430-F6779 uses the 128-pin version, not the 100-pin version. Looking at your connections, nothing wrong jumps out at me. For the many unused pins, they look fine, but you'll want to switch them to port function, output direction in your code. See Table 4-5 in the datasheet for more details. You'll want to make sure AGND and DGND get connected too.

Next, I would be sure to add the recommended capacitors for DVCC/AVCC (called CVCC), VDSYS1/VDSYS2/VASYS1/VASYS2 (called CVSYS), VCORE (called CVCORE), and AUXVCC3 (called CAUX3) pins. Also, make sure to add load capacitors for the external oscillator, XT1. Overall, refer to the schematic for the EVM430-F6779 as a reference for what to keep as you step back a level from the MSP430 connections and focus on the next level. For example, the schematic for the EVM430-F6779 includes sections like "Analog Power" and "Digital Power" which includes the recommended capacitors but also other smaller decoupling capacitors for better noise immunity. Finally, pay attention to the JTAG circuitry. The schematic has a "JTAG" section, but it features headers for alternating between 2-wire and 4-wire JTAG connections, so it may not be easy to replicate on your design. Refer to Figure 2-1 in the MSP430 Hardware Tools User's Guide for more details.

Hope this helps!

Regards,

James

MSP Customer Applications

Hello Dan,

I'm sorry for the delayed response. Let me address your questions.

Daniel Flohr said:

Meter layout well underway.  We are following your notes above and paying attention to the reference design.

Excellent! Nice work.

Daniel Flohr said:

1. Reference design says that the 12 pF Crystal caps are DNP.  You state above to populate them.   Please clarify.  ( Is watch Xtal even 100% required. Device will never go into low power mode.)

I would populate them. For some reason, the schematics in the reference design show these crystal load capacitors as DNP, but on all the EVMs that I have, they are there. Although I'm not the author, I'll submit a request to have this changed in the documentation. Basically, you can use the internal crystal load capacitors, but they are implemented in silicon and may not be as precise (which is important) as high tolerant, high precision load capacitors. Depending on which crystal that you select, the internal capacitors may not be adequate for the required effective load capacitance for the selected crystal (rare but possible).

Daniel Flohr said:

2. The reference design uses two pairs of three  0 Ohm jumpers to connect AGND and DGND.   Any guidance on that?

Most likely, this was done to implement a star ground to minimize noise between the analog and digital grounds. If any noise needed to be mitigated, then you could easily replace the 0 Ohm resistors with inductors instead. Check out these valuable resources about grounding techniques in mixed-signal systems.

Grounding in mixed-signal systems demystified, Part 1

Grounding in mixed-signal systems demystified, Part 2

Daniel Flohr said:

3. We intend to connect 4 wire JTAG exactly as shown in the reference without the jumpers as per this.   Trust it's OK

Since you're removing the jumpers, just make sure that you connect Pin 4 (EXT) of the JTAG connector to DVCC. On the EVM, Pin 2 allows the MSP-FET to supply DVCC when a jumper is across Pins 1 and 2 of JP10. You can see that the connections are very similar to what we recommend in Figure 2-1 in the MSP430 Hardware Tools User's Guide.

I hope this helps!

Regards,

James

MSP Customer Applications