Hi, I'm interested by what you have done. I want to use i2c to read analog value from a component.
The first solution that I found was to bitbang the i2c. But you, you use the i2c driver which is nice. Could you give us the peace of asm code that you use to interface with the MCP23017. And if you have the c code also it would be great. ( if possible, also the part of you managed to activate the module by writing MODULEMODE field into register CM_PER_I2C1_CLKCTRL register and also the code that wait for IDLEST field to confirm that module is ready). Micka, Le dim. 19 juil. 2015 21:45, Gianfranco Rosso <gianfranco.ro...@tiscali.it> a écrit : I've also posted this in I2C topic, the solution is there: http://beagleboard.org/Community/Forums/?place=msg%2Fbeagleboard%2FDAXyYJOrDIc%2FDZ8WKkRWaC0J Il giorno lunedì 13 luglio 2015 09:49:20 UTC+2, Gianfranco Rosso ha scritto: I want to manage the I2C1 module by the PRU, in order to interface some I/O expanders (MCP23017 by Microchip). I use may own "cape" without the plug-n' play eeprom (one of the next steps will be adding management for DCAN0 and DCAN1 so i'll need these pins too...). So, at present, there are just 2 MCP23017 connected to the P9.17 and P9.18. I load the *cape-universal* into slots and then I use *configure-pin* command to set P9.17 and P9.18 as *i2c* I've started from an example into the *am335x_pru_package-master* and wrote my own C PRU loader. Very simple, it just: loads the PRU codeinit the data exhanged with the PRUstart the PRUwait for ESC key presssignal to the PRU to stopwait for the PRU stopexit. Also the assembly PRU code is simple: init I2C1 module (by writing registers PSC, SCLL, SCLH, CON)init 1st I/O expander as 16 inputs (even if at power on it's already set as input)init 2nd I/O expander as 16 outputscicle reading status of inputs from 1st expander and echoing to the outputs of 2nd expanderexit cycle and halt when receive stop flag from the loader for send and receive I2C messages I use register SA, CNT, DATA and CON. That's very simple and linear... pity, it doesn't work. *I didn't see any activity at all in P9.17 and P9.18*. The PRU code is surely running, as I add a cycle counter and show it in the loader while it's waiting for ESC keypress, and also the PRU code correctly stops at the loader command. I was expecting that the PRU code stalls if I2C bus doesn't work, as there are waiting cycles both for STOP condition or for CNT reaching zero (depending on the write or read message sending). But it seems running, and running very fast also: the cycle counter is incremented to a very fast rate (over 550 kcycles/s) that's not compatible with the correct executing of I2C sequences (I've setted the module for 400Kbps rate... so the PRU cycle it's even faster than a single I2C bit time!). I'm surely doing something wrong, but I cant fugure what. Any idea? Suggestions? Inserisci qui il codice... .origin 0 .entrypoint START #include "iic_ioexp.hp" //costanti per l'accesso al modulo I2C1 #define I2C1_BASE C2 //base registri I2C1 nella tabella costanti #define I2C_SYSC 0x10 //offset del registro I2C_SYSC #define I2C_STAT_RAW 0x24 //offset del registro I2C_STATUS_RAW #define I2C_SYSS 0x90 //offset del registro I2C_SYSS #define I2C_CNT 0x98 //offset del registro I2C_CNT #define I2C_DATA 0x9C //offset del registro I2C_DATA #define I2C_CON 0xA4 //offset del registro I2C_CON #define I2C_SA 0xAC //offset del registro I2C_SA #define I2C_PSC 0xB0 //offset del registro I2C_PSC #define I2C_SCLL 0xB4 //offset del registro I2C_SCLL #define I2C_SCLH 0xB8 //offset del registro I2C_SCLH #define I2C_CMD_ENABLE 0x8400 //modulo I2C abilitato come master #define I2C_CMD_TX 0x0200 //modulo I2C in trasmissione #define I2C_CMD_RX 0x0000 //modulo I2C in ricezione #define I2C_CMD_START 0x0001 //modulo I2C richiesta generazione sequenza START #define I2C_CMD_STOP 0x0002 //modulo I2C richiesta generazione sequenza STOP //costanti per l'accesso all'I/O expander MCP23017 #define IO_EXP0 0x20 //7bit I2C address dell'I/O expander 0 (ingressi) #define IO_EXP1 0x21 //7bit I2C address dell'I/O expander 1 (uscite) #define IO_EXP_IODIRA 0x00 //indirizzo registro IODIRA dell'I/O expander #define IO_EXP_GPIOA 0x12 //indirizzo registro GPIOA dell'I/O expander //====================================================================== //macro che attende fine sequenza verificando generazione seqeunza di STOP .macro I2C_WAIT_BY_STOP _CHECK: LBCO r1.w0, I2C1_BASE, I2C_CON, 2 QBBS _CHECK, r1.t1 .endm //macro che attende fine sequenza verificando generazione seqeunza di STOP .macro I2C_WAIT_BY_COUNT _CHECK: LBCO r1.w0, I2C1_BASE, I2C_CNT, 2 QBNE _CHECK, r1.w0, 0 .endm //====================================================================== START: // clear that bit LBCO r0, on , 4, 4 CLR r0, r0, 4 SBCO r0, C4, 4, 4 //------------------------------------------------------------------ //configurazione modulo I2C1 //reset del modulo I2C1 MOV r1.w0, 0x0002 SBCO r1.w0, I2C1_BASE, I2C_SYSC, 2 MOV r1.w0, 0x0000 SBCO r1.w0, I2C1_BASE, I2C_SYSC, 2 // //attesa fine reset modulo //_WAIT_RDONE: // LBCO r1, I2C1_BASE, I2C_SYSS, 4 // QBBC _WAIT_RDONE, r1.t0 //configura prescaler e durata SCL H/L per avere 400kHz MOV r1.b0, 4 //prescaler=4+1 --> ICLK=SCLK/prescaler=100/5=20MHz (nel reference manual raccomandano circa 24Mhz) SBCO r1.b0, I2C1_BASE, I2C_PSC, 1 MOV r1.b0, 18 //durata SCL L=18+7 --> tLOW=1/ICLK*(SCLL+7)=1/20E6*(18+7)=1.25us SBCO r1.b0, I2C1_BASE, I2C_SCLL, 1 MOV r1.b0, 20 //durata SCL H=20+5 --> tHIGH=1/ICLK*(SCLH+5)=1/20E6*(20+5)=1.25us SBCO r1.b0, I2C1_BASE, I2C_SCLH, 1 //abilita modulo MOV r1.w0, I2C_CMD_ENABLE SBCO r1.w0, I2C1_BASE, I2C_CON, 2 //------------------------------------------------------------------ //inizializzazione IOEXP 0 //indirizzo slave MOV r1.w0, IO_EXP0 SBCO r1.w0, I2C1_BASE, I2C_SA, 2 //n. byte da spedire MOV r1.w0, 3 SBCO r1.w0, I2C1_BASE, I2C_CNT, 2 //riempie FIFO MOV r1, IO_EXP_IODIRA | 0x00FFFF00 //tutti i pin come ingressi (in realta' e' gia' cosi' dal POR) SBCO r1.b0, I2C1_BASE, I2C_DATA, 1 SBCO r1.b1, I2C1_BASE, I2C_DATA, 1 SBCO r1.b2, I2C1_BASE, I2C_DATA, 1 //attesa bus free _WAIT_BB: LBCO r1, I2C1_BASE, I2C_STAT_RAW, 4 QBBS _WAIT_BB, r1.t12 //comando scrittura MOV r1.w0, I2C_CMD_ENABLE | I2C_CMD_TX | I2C_CMD_START | I2C_CMD_STOP SBCO r1.w0, I2C1_BASE, I2C_CON, 2 I2C_WAIT_BY_STOP //------------------------------------------------------------------ //inizializzazione IOEXP 1 //indirizzo slave MOV r1.w0, IO_EXP1 SBCO r1.w0, I2C1_BASE, I2C_SA, 2 //n. byte da spedire gia' impostato //riempie FIFO MOV r1, IO_EXP_IODIRA | 0x00000000 //tutti pin come uscita SBCO r1.b0, I2C1_BASE, I2C_DATA, 1 SBCO r1.b1, I2C1_BASE, I2C_DATA, 1 SBCO r1.b2, I2C1_BASE, I2C_DATA, 1 //comando scrittura MOV r1.w0, I2C_CMD_ENABLE | I2C_CMD_TX | I2C_CMD_START | I2C_CMD_STOP SBCO r1.w0, I2C1_BASE, I2C_CON, 2 I2C_WAIT_BY_STOP //------------------------------------------------------------------ //ciclo rinfresco I/O _LOOP: //------------------------------------------------------------------ //legge ingressi //indirizzo slave MOV r1.w0, IO_EXP0 SBCO r1.w0, I2C1_BASE, I2C_SA, 2 //n. byte da spedire MOV r1.w0, 1 SBCO r1.w0, I2C1_BASE, I2C_CNT, 2 //riempie FIFO MOV r1, IO_EXP_GPIOA SBCO r1.b0, I2C1_BASE, I2C_DATA, 1 //comando scrittura MOV r1.w0, I2C_CMD_ENABLE | I2C_CMD_TX | I2C_CMD_START SBCO r1.w0, I2C1_BASE, I2C_CON, 2 I2C_WAIT_BY_COUNT //n. byte da ricevere MOV r1.w0, 2 SBCO r1.w0, I2C1_BASE, I2C_CNT, 2 //comando lettura MOV r1.w0, I2C_CMD_ENABLE | I2C_CMD_RX | I2C_CMD_START | I2C_CMD_STOP SBCO r1.w0, I2C1_BASE, I2C_CON, 2 I2C_WAIT_BY_STOP //legge i byte ricevuti LBCO r2.b1, I2C1_BASE, I2C_DATA, 1 LBCO r2.b2, I2C1_BASE, I2C_DATA, 1 //------------------------------------------------------------------ //scrive uscite //indirizzo slave MOV r1.w0, IO_EXP1 SBCO r1.w0, I2C1_BASE, I2C_SA, 2 //n. byte da spedire MOV r1.w0, 3 SBCO r1.w0, I2C1_BASE, I2C_CNT, 2 //riempie FIFO MOV r2.b0, IO_EXP_GPIOA SBCO r2.b0, I2C1_BASE, I2C_DATA, 1 SBCO r2.b0, I2C1_BASE, I2C_DATA, 1 SBCO r2.b0, I2C1_BASE, I2C_DATA, 1 //comando scrittura MOV r1.w0, I2C_CMD_ENABLE | I2C_CMD_TX | I2C_CMD_START | I2C_CMD_STOP SBCO r1.w0, I2C1_BASE, I2C_CON, 2 I2C_WAIT_BY_STOP //------------------------------------------------------------------ LBCO r2, CONST_PRUDRAM, 0, 4 ADD r2, r2, 1 SBCO r2, CONST_PRUDRAM, 0, 4 //------------------------------------------------------------------ //esce dal ciclo e se il flag di uscita nella ram condivisa e' azzerato LBCO r2, CONST_PRUDRAM, 4, 1 QBNE _LOOP, r2.b0, 0 _EXIT: //invia all'host la notifica di programma completato MOV R31.b0, PRU0_ARM_INTERRUPT+16 HALT -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
